Tournaments are low risk for high reward. Small entry fee can result in huge payday. Biggest drawback is the extreme time involved, many long hours in a single day or even over multiple days. Obviously a very rare occurrence to win a big score via tournaments but it can and does happen for relatively low costs.
Cash games are high risk for low reward. You put your entire stack of chips at risk every hand you play and unlike tournaments, those are
real money chips, not pretend. Yikes! For risking all that at once, your reward is capped to just doubling the size of your own stack (save for a very rare multiway pot). You play a few hours and if you walk away with twice as much as you began with, that's a big success but it won't happen every time. Rarely you'll make a big score, but it will only be a few multiples of your buy-in. Biggest plus about cash is you can join almost instantly and quit whenever you feel like quitting. There's no scheduling or planning involved like there is for tournament players. Play cash at your full convenience, a huge factor for most.
Cash is all about consistency over many many hands. Slow but steady accumulation wins the race. Tournaments are all about the slow drip of loss after loss after loss, many many hours of patient failures... all so one day everything goes right and you make a final table and win more than all the money you've paid to play tournaments for the past few months or even years... and you begin the whole waiting game process again, looking for those big days and big scores.