[p. henry]

As I read it, registered voters are a subset of adults and likely voters are a subset of registered voters.

[Bonaparte]

A poll of "adults" makes no distinction as to whether anybody is even registered, let alone a "likely" voter. Obviously, the poll is not measuring the opinions of children, so it goes without saying that all respondants are adults. The important thing here is that this was an unusually large random sample and the sample consisted of both registered voters and likely voters.