Actually, MDA is made first, and then you can either leave it as is, or branch either way to MDEA or MDMA.
There are definite differences in the feelings the 3 give you, but even the most experienced users will have trouble distinguishing. Generally, MDA is considered "speedy", MDEA is "smacky" and MDMA is sort of "everything" although these are VERY subjective, as a dose of speed can make MDEA speedy, a very strong dose of any of the above can feel "smacky" and a hundred other variables.
Generally, it's agreed that MDEA lasts the shortest, MDMA middle and MDA the longest. But basically, don't concern yourself with it - it's too hard to tell.
Cat