They are very similar. Rumor is that they're made in the same place - both made in Vietnam. I had the Phoenix Decathlon and thought it was pretty nice. I was amazed at what I got in the package for the price I paid. I was able to use all the hardware and assembly was pretty easy, except that the wing strut directions are not very clear. Easy to figure out though.

Plane looks great on the ground and in the air, flies really nice.

Again, Seagull and Phoenix are very similar, and identical in quality and features.