odds vs odds vs... equity?

I have a question, and I think it's mostly a terminology question, although help with the basic concepts would be appreciated.

I think I understand drawing odds. If I have pocket aces, and one is a spade, and the flop hits 567 all spades, then I have to draw to the flush to be sure I have the nuts. There are 47 unseen cards, and my outs are the 9 unseen spades. 47 unseen cards divided by 9 outs means 5.2:1 drawing odds to make the flush.

(BTW, I usually just see this called "odds." I have seen it called "actual odds" a few times. So far as I know I invented the term "drawing odds," and that label makes the most sense in my head. Feel free to use my new poker term free of charge [img]/images/graemlins/wink.gif[/img].)

I also think I understand pot odds. Say I'm playing 10/20 after the flop in late position, with a bet and two calls ahead of me and two pre-flop betters to act after me. On my action the pot has $90 in it. I'll be getting 9:1 pot odds for my $10 post flop bet. That's plenty good pots odds for my flush draw.

I even think I understand implied odds. In the example above there were five players including myself that called the big blind. No one projected strength by raising pre-flop (although I SHOULD have if I were holding pocket aces [img]/images/graemlins/wink.gif[/img]). Then the small blind bet, and it was called around to me with two people yet to act.

With no one projecting strength either pre or post flop, there's a very good chance that the two players yet to act will also call. In that case, I can add their $10 each to the $90 already in the pot for a whopping 11:1 implied pot odds. In this case I'm buying that turn card wholesale.

The rule of thumb here being that, all other things being equal, if your pot odds are better than your drawing odds you should bet and in the long run you will make money.

I think I've got a handle on things so far. Now comes the part I'm shaky on.

Say the two players to act after me both fold. With $100 in the pot the turn comes an ace. The small blind bets $20 and the other players all fold around to me. His $20 plus the $100 already in the pot give me 5:1 pot odds if I bet, and that's near exactly my drawing odds.

BUT..

From this point on in the hand it's just me and the small blind heads up. That means for every bet I put in the pot I'm only getting one other bet to go into the pot, rather than the five bets I got both pre and post flop.

What is the name for this? Is this called "pot equity," or is that something else?

Regardless, I have read that I should fold here, since my turn bet and inevitable river bet will only be getting 1:1 "what ever this is called" and my odds for making the flush on the river are much higher than that.

So, my question is can someone please tell me the correct name for "what ever this is called" and direct me to a good treatment on how it relates to drawing odds and pot odds?