Mopar engine differences

Short block is an engine assembly without the heads, a long block includes the heads and valvetrain. It used to be if you blew your bottom end you couled order a short block from a reman house and swap your top end over. Big/Small block is sort of self explanatory different cast blocks to handle different bore /stroke configurations ,Ill go out on a limb here andsay a small block is up to 4 inch bore big block is bigger than 4 inch bore typically hence the need to cast a beffier block. Im zsure someone woill be along to say everything I just typed is wrong but thats how I remember it from my time in the wrench biz...of course ever since the internet everything I know has somehow changed :)