Most Plinko is played in a browser. Standalone apps exist, and the useful question is what a given app actually is before it is installed.
Browser first
Plinko implementations are built in HTML and run in a mobile browser without installation.
For most people that is the whole answer: the game is identical, there is nothing to install
and nothing to update.
What "Plinko app" usually means
Searches for a Plinko app return three different things, and they are worth telling apart:
An operator's own app containing many games, Plinko among them.
A free standalone game with no real money, essentially a toy.
An unrelated app using the name — the term is popular enough to attract them.
Before installing anything
Check who publishes it. A licensed operator's app names the company; the licence number
usually appears in the listing.
Check the permissions requested against what a game needs. A Plinko game does not need
your contacts.
Prefer the operator's own site as the download source over a third-party mirror, and treat
files distributed outside official channels with suspicion.
Worth knowing. An app cannot offer better odds than the browser
version of the same game — it is the same engine. Any app promising improved chances is
promising something it cannot deliver.