Core answer: story, town, farming, mysteries, and atmosphere stay the same on both modes. The split is how hard combat, mining interruptions, sleep and bath tradeoffs, and Old God pressure hit you. Cozy cuts combat pressure hard while keeping the full narrative; Old Gods is the design the game is built around, where rest has a cost and fleeing is a real action.

1Pick the Mode That Matches Your Problem

2Do This on Day 1 Either Way

Decision Points After the First Week

You Are FeelingDo This
Mining and chopping keep starting fights and you are brokeDrop to Cozy, or only mine when stocked with heals and a weapon equipped.
Fights are boring and you want the horror half to biteMove to Old Gods or a harder setting; stop fleeing every random and start cooking combat food.
Curses feel like noiseYou are on Cozy. Fine. Ignore them or take a bath when the text piles up.
One boss walls youSunday Kaal (or the god matching the damage type), then restock heals before the mall.
Combat basics: spend AP, build combat points for heal, evade, and crit procs, use items and rituals, and watch temporary curses. It is not button-mash combat.

Common Mistakes to Avoid

30-second answer: want Stardew-with-wrong-vibes, pick Cozy. Want a combat tax on the farm loop, pick Old Gods. Unsure, pick Normal and change later. The town, farm, and mysteries are the same either way.