I’ve learned a maamar on gan Eden vs. Yemos
haMoshiach which are both termed Olam haba.
I’ll share the applicable nugget I remember happy to refer you further if desired…
Basically gan Eden rewards the neshama and personal perfection represented by the learning of Torah as Torah changes ones mindset and thereafter middos, and brings ultimate refinement to a person.That’s why not everyone gets there.
Moshiach rewards the body and refinement of the world, accomplished by the avoda of Maase hamitzvos. Since every yid does mitzvos, every yid (neshama at least there’s a whole other discussion regarding gilgulim) will be part and earn it. And it is even loftier than gan Eden which is why all the neshamos of the greatest people like the avos etc will leave gan Eden to have tchias hameisim and enjoy yemos hamoshiach.