Oh, for the 2 or 3 people out there who don't know the difference, here. Standard Lego is about 8 times smaller than Duplo.
Both boys play with the Lego/Duplo but Corwyn LOVES it. Here are some shots of the evolution of his play with the blocks. His Duplo use started out building 'Trains' and then square towers with all the blocks filled in, onto creations with a ton of imagination. He started to figure out bridges, stairs and supports. Then I messed him up with the smaller bricks. He likes to build with the instructions and for the couple of new sets they got, he did that first, but he's back to first love of turning everything into a 'train'. He even put the horses on wheels so they could join in. The Lego motorcycles are a huge hit too.
So far they have a teeny tiny bit of the Lego available. My place is not big enough for all of it to be out and they are not ready. But I'll keep adding more bricks and blocks over time.
I can't wait to see what he creates with the Lego!