well, I'm just starting to mess around in cash games a bit, but feel very comfy and confident with tournaments....so we may have complimentary perspectives.
anyways, there are lots of ways in which the 2 overlap (ex. implied odds
, playing the player, knowing your table).
what's more interesting is the ways that the 2 differ.
here are my top thoughts on important differences
Stack size management
probably the number one consideration in tourney poker. you can't manipulate your stack size to stay in your favorite "zone" so to be successful you'll need to be competent and playing many different stack sizes. There are different tourney strategies for each stack size and you'll need to be able to employ all of them and know when to change gears
situation reading more important than player reading
obviously your player read is extremely important in all forms of poker, including tourneys but not as much as in a cash game. Because tables are frequently breaking your ability to quickly size up a new situation and new table and play your specific stack size well considering the other stack sizes at the table is all more critical to your long term success than to have a dead read on a particular villain's light 3betting range...
value of tournament life is a factor
this concept doesn't really come up in cash, and sometimes even in tourney poker many players are quick to say "I play for first. I'm not afraid to bust out" and that's generally a good thing but you CANNOT throw caution to the wind in a tourney. I'm sure you've heard the saying "a chip and a chair" and in short because it is possible to turn 1 chip into a min cash or even first place it means that each chip in a short stack has exponentially more value than the same chip in a big stack. What does all that mean in practice? sometimes in a tourney you need to pass up a slightly +EV spot if it puts your tourney life, or even a big chunk of your stack in jeopardy. Maybe if you're going to try a big river bluff, you don't go all in, you just bet most of your stack which leaves you 10bb behind just in case you get called. Might sound like scared poker; but it's just smart tourney poker. Smart tourney players are a bit more cautious in marginal situations than smart cash players would often be in that same situation.
The metagame is not as big of a deal at a full table
so for instance, showing a bluff early on to set up a big payoff later is not often going to pay off in a tourney. I mean, it could and I've done it and seen it done, but it is generally going to be more of a straightforward experience. that doesn't mean nobody bluffs, but making -EV plays with the intention of capitalizing on that "image" later is probably not real smart in tournaments.
You'll need to learn strategies to cope with all styles
in a cash game if Phil Ivey gets seated to your left, and starts beating you out of every pot, then you can just quit for the day, move to a different table, go get dinner etc. In a tournament you have absolutely ZERO control over who will be on your right or left. so...this kind of goes hand in hand with the playing the "situation" thing but for example if you're 2nd in chips in a large MTT on the bubble, but unfortunately the chip leader is on your left and he is a LAG and keeps playing back at you, well then you're probably gonna have to NIT up a bit. Good tourney players can adjust their style in the blink of an eye to accommodate ever changing table conditions and stack sizes.
Well...that's a lot. I'm sure there is much more I've missed.
I'm surprised nobody else has chimed in yet.
I'd be VERY interested in hearing (as you gain experience) the biggest differences from cash in YOUR perspective. I still feel like a fish at most cash tables...