A library for every store, or a library for retro
Playnite is a general launcher. Steam, Epic, GOG, and a long plugin list sit next to emulators. It is open source, free, and the right answer if most of what you play is a store library with a few ROMs on the side.
RetroApp does not try to be Steam. It does not log into Epic. It scans retro dumps, attaches console metadata, and adds sessions and cloud saves. The plugin ecosystem is smaller because the job is narrower.
Emulator setup
Playnite can launch RetroArch and standalone emulators through extensions. You still install the emulator, still set the BIOS folder, still pick the core. That is honest software: it does not pretend to be the emulator.
RetroApp hides that path for the consoles it supports. The first PS1 game still needs your BIOS dump. After that, the core choice is not a plugin you maintain. If you enjoy tuning PCSX2 flags every week, Playnite plus the standalone emulator will feel more honest. If you want the game on screen, RetroApp is the shorter route.
When the generalist wins
Choose Playnite if the shelf is mixed: a new release on Steam, an old GOG installer, and a SNES ROM. One fullscreen mode for all of it is the point of Playnite. RetroApp will look empty next to a 400-game Steam library because those games are out of scope.
Choose RetroApp if the shelf is cartridges and discs, and the thing you actually lack is other people. Playnite will not open a netplay room. A plugin will not sync a memory card between two houses. That is the column in the table above that is not a matter of taste.
Plenty of people can run both. Playnite for the stores, RetroApp for the retro library and the sessions. They are not fighting over the same button.
Download RetroApp · BIOS guide · Save states · Best retro launcher · vs LaunchBox · vs Playnite · vs EmulationStation
RetroApp vs Playnite is a launcher comparison. Specialized emulators stay better at their one console. The table above is the feature split. The text is the part that should decide the install.