Length and replay value
This is the real difference and the one that should decide it.
It Takes Two runs across a series of themed worlds, each with its own pair of abilities, and the structure means it keeps surprising you right up to the end. It is a project - something two people arrange to continue on Thursday - rather than an evening.
A Way Out is a single story with a single ending, and the surprises are the content. Once you have seen it, there is very little reason to start again, and both players know how it goes. Treat it as one exceptional night rather than a purchase to get months out of.
We do not publish hour counts because they vary enormously with how much a pair talks and how often they get stuck, and a precise figure would be invented rather than measured. The shape is what matters: one is several evenings, the other is one or two.
Tone
It Takes Two is bright, comic and inventive - a couple turned into dolls trying to save their marriage, with a talking self-help book. It is genuinely funny and entirely suitable for a wide range of ages, which is why it appears on our couples page and family guide.
A Way Out is a grim, adult crime story - two convicts breaking out of prison, with violence and swearing throughout. It is well told and it is not a family game.
If tone is the deciding factor rather than length, that difference is larger than anything mechanical between them.
Price
A Way Out is the older and cheaper of the two, and both benefit from the Friend's Pass making one purchase cover two people. Live prices for both are at the top of this page. Given how much more game It Takes Two contains, the gap in price is usually much smaller than the gap in content - which is why we recommend it first even to people on a budget. Our cheap games guide covers the wider budget question, and Portal 2 is the genuinely low-cost two-player alternative.
What about Portal 2?
It comes up constantly in this conversation and deserves an honest mention: a separate two-player co-op campaign, split-screen or online, usually a few dollars, and still one of the best co-op games ever made. It is a puzzle game rather than a story, so it scratches a different itch, and it is the best value of the four by a wide margin. Portal 2 versus It Takes Two covers that pairing directly.
The verdict
It Takes Two is the better purchase for almost every pair - more game, more variety, and a tone that suits a wider range of people. A Way Out is the right call when you specifically want one complete story told in an evening or two, and with the Friend's Pass that is a cheap and memorable night.
Play It Takes Two first, then come back for A Way Out when you want something shorter. Our reviews of It Takes Two and A Way Out go deeper on each, and the co-op campaigns page lists the rest of the games with a real ending.