outside of the leaves having a sheen and both show leaf blight in late summer the similarities end. Persimmon is a typically smaller tree growing on wooded edges and the wood is nearly all white and splits fairly normal. Black gum is another that will also grow in wooded edges but heart wood is dark, growth rings will be much larger and it splits like sweet gum.
I had a couple gum trees a few years ago. Really heavy when wet, very light when dry. Split fine for me, but I use a hydraulic splitter. There was some very light yet strong wood in the middle. Like balsa wood. And when dried it would light with a lighter/match. I saved buckets of shards to use as firestarter for years. but finally ran out.
Sweet gum balls are a good firestarter when brown. Others have mentioned the same with pine cones in other posts.
I've burned Sweet Gum and...it burned...but it was so unexciting that it probably wasn't all that great. It's a tree I love and hate. I really like the fall color, but I hate the spiky balls they drop and how quickly they take over. I use a hydraulic splitter, so if one falls over or is in my way, I'll gladly take it as long as it's not taking up the last usable space Hickory, Ash, Maple or Locust could be sitting in.
I recently joined this site and didn't know over the years I should have been taking pictures of my wood hoarding...I wish I took a pic and kept it to share... Before the demolition derby was banned from our county fair, I used to run the demolition derbies every year. I had an 80's Cadillac Fleetwood Brougham that I smashed up in one. I was waiting for scrap prices to go up in the late winter/early spring and I was using the car to store my excess wood that I was scrounging all winter long for the next year. Here's the car...before and after...but never took one with my wood stash in it.
Will I cut down a sweet gum? Yes, I will cut down anything that I can burn. As someone stated, when it is dry it weights nothing. Sweet gum is harder to split but I used my little hydraulic splitter and did not have any problems. I think the poplar gave off more heat than the sweet gum. I think I have burned all the sweet gum I cut.