A hand like A7o is a strong hand, but does not flop flush draws or straight draws often (and a higher % of the time no action or chopped action happen when they do).A hand like 98 is not a premium hand, maybe not even considered strong, but it flops very well (straight draws, flush draws if it's suited and some decent pairs that can often be value bet or call bets heads up).And then you have hands like QQ that are just premium hands, very strong.---Let me know if that gives you a good enough idea.

Traditionally, premium hands in say a 9 handed game are basically QQ, KK, AA, and AK and that's it (AQ is easily behind in less aggressive games if you are 4 bet, or in any game if you face a raiser and a reraiser, or a even a raicer and a caller). In heads up I think AQ, AJ, 88+ are basically premium hands in my book. AJ and AQ depends on the player and stack depth too but even in 9 handed games you have to think carefully about whether your QQ and AK are beat even though they are premium hands. 88+ is super good in headsup since to me 88 seems to be the magic spot where you're generally flipping against a shoving range when your stacks are around 20 - 50 bbs, over 50bbs you start coming less of a favourite (but still may be correc to get it in pre) I think and less than 20 bbs 88 becomes stronger and basically the nuts.