To me, EE is much more intense than BTMR. Like others have said, faster and higher.
The first time I rode EE some years back, I thought it was my new favorite coaster at Disney. When we returned to Disney a year later, I noticed the backwards twisty type movement really got to me, making me feel odd and not in a good way. After that, I only wanted to ride it once per trip. I rode it during our last trip two years ago only once and decided I will not be riding it again.
Please note, I am in my 50s and used to do all the coasters, including Rockin Roller Coaster (I stopped doing Rockin a few years ago and will not be riding it again). The older I get, lol, certain rides have started to bother me and with EE it is that backwards twisty movement that I don't like at all. It's not that it is so scary, it's more that I don't like the feeling it gives me.
The big hill is fun, but there is a point when you get down to the bottom of the hill, there is a feeling of being forced down to your seat. Again, not really scary, just a strange intense feeling that, when I first rode it some years back, I thought was big fun. Now, it just feels intense.
I can ride BTMR once a day... twice a day if those times are hours apart. I don't find it at all scary, it's fun, but it just jostles me about too much to do it two times in a row. I can ride Splash and stay on that ride all day, not that you asked, lol. I have limited my SpaceM riding to once or twice per trip, but I'm not so sure I'll be going back on that again either. I used to love it!
I would say that it would be fine to try EE once and after that, you can decide if it's fun enough to do again, but just know that Big Thunder is actually Little Thunder compared to EE, imo. Good luck!