In England “elastics” are footwear, in North Carolina they are knitted products used in clothing and home furnishings needing some expandability. In New Hampshire, the term “elastics” is used by old-timers in lieu of “rubber bands.”
In most locations, the term “elastic band” refers to thin, stretchy strips made of cotton, polyester, acrylic, nylon, and rayon. These expandable bands are used in fabric-based product manufacturing. “Rubber bands,” on the other hand, are usually made of rubber and latex, and are used to hold multiple objects together.
New Hampshire and Massachusetts are the only locations where I have ever heard the the term, “elastics” used to describe that thin, stretchy item used to gather one's hair into a pony tail, or to keep a bunch of one dollar bills in a neat pile. The term was being used this way as early as the 1950s and as recently as this year (when I heard it used by a family member).
P.S.: The term “elastics” is not to be confused with “rubbers.”