I started out a live tourney player, and have now switched pretty completely to online ring games. Cash is much much simpler at a basic level. Simple math can dictate your decisions without need for concern about ICMs and the such. Also it is all just one really long session, so I feel like a lot of the bad luck brain crushings get cut down, as is supported, I feel, by the fact that you can rock a cash game with a higher percentage of your roll than a tourney and still be rocking proper BRM.
However, cash is much more intricate as you become more advanced. Every hand can be played with any opponent for stacks at any time on the merit of that single hand, not concerns about being knocked out, or effects on future stack sizes. Due to this play can be much more intricate and complex postflop. This is great for your bottom line if you can get a grip on it, because this means that oppoents are free to make their mistakes bigger and more often, thereby paying you more. Player dependent reads can also go up in value as you wind up playing many people over many
hands, and typically in much more similar game conditions than in tourneys where shrinking M's lead to large changes in player actions.
So cliff notes are, drawing hands go up in value substantially, and big card hands lose some. This effect is greater at full ring, and lesser at 6max. Set mining also becomes much more valuable. Learn the pot
odds you need for various numbers of outs well, and practice up on estimating implied odds(err to guessing too small).