Which is more fun too shoot does the 55gr blow apart cans better? Which would be bettter suited for home defense?  are they physically identical
because my gun functions with the FMJ will it do the same with the hollow points from the pic they don't look much different.

I'll try to answer your questions in reverse order.

Just because your rifle works with 55gr FMJ doesn't mean it will work with hollow point ammo. The only way to know for sure is to test fire with the ammo you are interested in.

FMJ and hollow point ammo may look the same in a picture but they are not, their construction is completely different.

I cannot answer your question about which type is better suited for home defense. FMJ ammo has greater penetration  - this may or may not be a good thing.

You need to decide which type is more fun to shoot yourself..I'd suggest you fill the cans with water before you shoot them.

Well thanks I do fill the cans, bottles jugs with water that don't fair too well against the 223 though. I filled a 5 gallon with water and shot it at about 25 yards, it just destroyed it the whole thing blew apart, lots of fun I was thinking I should fill them with jello?

Why should I stick with 223 FMJ's wouldn't Hollow points be more fun?

huh?

Nevermind, I get it now.  

I only use HP in indoor ranges where you can't shoot FMJ.  Use whatever is cheaper since you are just plinking anyways, save the FMJ for when the SHTF.