Should I do anything about my 2 year old, who seems to be behind his other peers? please read.

My husband and I have been noticing that when we take our son to the playground, he seems to be behind in his learning as far as play goes. For instance, other two year olds are able to balance themselves while using the slide, (holding their heads up), our son can't seem to do that...also his other peers, can hang on bars with their feet in the air, and he cannot, other kids crawl through tunnels and our son doesn't get the concept of crawling through, he just scoots through....finally, our toddler towers over the other two year olds, because most people think our son is 4 or 5, how do we handle these situations? He has a lot of fun, so we figure that's all that matters. Doctors have said that he's fine and will catch up, but he doesn't seem to be. Help. Thanks to all who took their time to read this.