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Knex vs Legos: What’s The Difference and Which Is Best?

Both LEGO and K’Nex are construction toys that encourage the principles of Science, Technology, Engineering, Art, and Mathematics (STEAM) with children as young as 3 years old.

This is achieved through the use of plastic bricks, rods, motors, and many other accessories. The sets allow children to create structures that are simple or highly intricate and everything in between. 

Both of these systems offer children the opportunity to learn STEAM subjects while still having amazing fun playing. LEGO and K’Nex have always appeared on our toy shelves at home both with my daughters and sons from a very early age. 

Main Differences Between Lego and K’Nex


K’Nex is a much cheaper option than LEGO as a construction toy or set. LEGO sets can range in price from $40 to hundreds of dollars for the newer, more tech orientated sets. This can be off-putting as a parent.


Although both products are made from high-quality materials that will last a long time. LEGO is more durable than K’Nex.


K’Nex is great for creating complex and intricate designs. But LEGO is catching up in this respect with the launch of LEGO Technic but the pricing of some of these sets will blow most peoples budget right out of the water.

Main Similarities Between Lego and K’Nex

Material Quality

Both products are made from high-quality materials, meaning that they can easily stand the stresses and strains of being played with every day.


The easier that children are able to connect their toys with their own reality the more fun they have playing with them. Both LEGO and K’Nex exhibit these connections to real life allowing children to take the knowledge and understanding and apply it elsewhere. Playsets like these allow children to have more fun and be more enjoyable.


Both products use non-toxic materials in the construction of their toys making them child friendly.


Again both are lightweight, making them easy to transport. This means that they can be carried and played wherever and whenever they want. If you are considering taking a large set of LEGO, do note that they are slightly heavier than the K’Nex systems.

Product Reviews

We have looked at both LEGO and K’Nex and the wide range of sets that they have available. Here are some of our favorites that show the range and versatility of both products.

1. Kid K’Nex – Budding Builders Building Set

Kid K’NEX – Budding Builders Building Set – 100 Pieces – Ages 3 and Up – Preschool Educational Toy

Product Information

  • Pieces: 100 pieces
  • Age Range: 3 years and up

This K’Nex set is a great introduction to this toy as it contains 100 large pieces that are brightly colored and easy for small hands to manipulate.

The set includes 50 building ideas ranging in difficulty from basic shapes to more advanced designs.

Although, the set includes building ideas K’Nex allows your child to use their imagination and create absolutely anything that their imagination can imagine! 

This is also a great introduction to STEAM principles and because it is so easy to use children will love to build their own figures all by themselves and they will also love to follow your lead and build more advanced structures.

Pros of K’Nex

  • A great introduction to STEAM toys
  • Large pieces that are easily manipulated by small hands
  • Lightweight
  • Comes with own storage box.
  • Durable

Cons of K’Nex

  • Some pieces are too flexible and bend easily
  • Some reviews have complained that the instructions are too difficult for children to follow
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2. K’Nex Coaster Building Set

K'NEX Thrill Rides - Clock Work Roller Coaster Building Set – 305 Pieces – For Ages 7+ Engineering Education Toy

Product Information

  • Pieces: 305 pieces
  • Age Range: 7 years and up

This set is a progression not only in the number of pieces but also that the structure is motorized. This set is designed to help children to build a fully functioning motorized rollercoaster.

The red car is lifted to the top of the coaster by a clock arm and once you let go of this arm the car screams along the track following all the twists and turns of the coaster you made. The coaster stands around 2.6 feet high when complete.

It is designed for children aged 7 and up and although it contains almost three times the pieces of the smaller set above it does only come with the instructions to build one structure – the roller coaster.

But the great thing about K’Nex is that they are compatible with all the other K’Nex sets allowing children to make bigger, more imaginative creations.

Pros of K’Nex

  • A great STEAM development toy
  • Durable
  • Easy to follow instructions
  • Lightweight
  • Ability to add to other K’Nex sets

Cons of K’Nex

  • Will require batteries
  • Small parts can be easily misplaced
  • Mixing sets means that you may not be able to rebuild a certain structure.
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3. LEGO City Space Mars Research Shuttle

LEGO City Space Mars Research Shuttle 60226 Space Shuttle Toy Building Kit with Mars Rover and Astronaut Minifigures, Top STEM Toy for Boys and Girls (273 Pieces)

Product Information

  • Pieces: 273 pieces
  • Age Range: 5 years and up

This set is designed to build one specific piece, in this case, it is the Mars Research Shuttle and Mars Rover. It comes with 2 LEGO City Mars astronauts, plus a helidrone and a storage drone.

This set is a great introduction to STEAM and also encourages open-ended play allowing children to use their imagination.

This is a great set to spark the imagination and is a set that you can actually play with although I suspect it would end up with some missing pieces rather quickly. 

Pros of LEGO

  • Durable
  • Portable
  • Really good instructions
  • Easily added to other sets

Cons of LEGO

  • Expensive
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4. LEGO Technic Liebherr R 9800 Excavator

LEGO Technic Liebherr R 9800 Excavator 42100 Building Kit (4,108 Pieces)

Product Information

  • Pieces: 4108 pieces
  • Age Range: 12 years and up

This area of LEGO is a step up from their traditional blocks and is very much aimed at older children and even adults. LEGO Technic has a range of different projects from cars, to bikes, to buildings and so on.

The idea behind these LEGO sets is to offer children the opportunity to learn more advanced elements of engineering. This particular one is powered by 2 advanced smart hubs with 7 motors it is a huge step up from the LEGO spaceship.

A further and more advanced introduction to STEAM for ages 12 and up.

Pros of LEGO

  • High quality
  • Further developing STEAM features
  • Engaging software
  • Clear instructions

Cons of LEGO

  • Age restrictions of 12 plus
  • Very expensive
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Is K’Nex Compatible With Lego?

You can get a Universal Construction kit that allows for compatibility between not only K’Nex and Lego but also a range of other construction toys such as Duplo, Krinkles, Gears! Gears! Gears!, Lincoln Logs, and loads more.

This opens the world up for these construction sets by allowing children the opportunity to make structures that they could then potentially run their Lego vehicles on or through.

LEGO vs K’Nex – The Winner Is?

This is a tough call to make as my household are huge fans of both these construction toys. But the best toy for you will depend on the age of the children that you are purchasing it for and how much you really want to spend.

Honestly, if you are looking for a good durable toy that can grow with your child, help them to produce realistic structures and even more intricate design while still not breaking the bank then K’Nex is the right choice for you.

The Final Thought

Construction toys are a great addition to any child’s toy store and whether you decide on K’Nex or LEGO as your construction toy of choice you will not be disappointed.