Mastodons and Mammoths

I used to think that mastodons and mammoths were the same.
Of course, if that were accurate, then why a second name?
The two proboscideans sure are easy to compare.
They both were prehistoric, had an awful lot of hair
Compared with modern elephants, and grew their tusks real long.
But deeming them one taxonomic family is wrong.
Consider etymology for getting at the truth:
The mastodon had nipple-like protrusions on a tooth,
Specifically the molar, meant for eating leaves and brush.
The mammoth’s sported ridges for the grass that it would crush.
The tusks were also different, as the mammoth’s curved around;
The mastodon’s were relatively linear, we’ve found.
The mammoth had a most distinctive knob atop its head.
It also had a fatty hump for times it wasn’t fed.
The mastodon was shaggier and had a longer tail
And bigger ears but otherwise was not as great in scale.
Its habitat was sylvan, while the mammoth mainly strode
A periglacial landscape called the steppe for its abode.
I could continue talking, but I’d rather be succinct,
Espec’ly when the creatures I’m comparing are extinct.