They are both choline. The difference is what the research shows and what they cost.
Choline bitartrate
Choline bound to tartaric acid. It is by far the most common form on shelves, and the reason is economics: it is inexpensive to produce, so it is the default choice when a formulator needs to be able to write "choline" on a label without much of the budget going to it.
The evidence in healthy adults is the weak point. One 2026 trial gave healthy adults 1,650 mg of choline bitartrate and found no difference in working-memory performance against placebo — though brain activation did change. That is a narrower finding than "it does nothing", and it is worth stating narrowly.
Alpha-GPC
A highly bioavailable form, and the one behind most of the clinical research on choline and cognition. Review-level evidence describes it as able to cross the blood–brain barrier.
It costs meaningfully more per gram than bitartrate. That single fact explains most of what the supplement aisle looks like.
How to tell them apart in ten seconds
Turn the pack over and read the ingredients panel. The word next to "choline" is the answer. There is no trick to it and nothing is hidden — it is simply a detail almost nobody checks.
Then check whether the milligrams are printed at all. If the label says "proprietary blend", the amounts are legally allowed to be withheld, and that is usually why the phrase is there.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Sources for every figure, with the population studied in each, are on our citations page.