Hi Luis,
Kind of looks like you're out of luck; you don't mention if you have the 38 or 42 mm model, but in both cases the cellular vs. GPS versions take batteries with different part numbers and slightly different mAh ratings, so outside of someone who can definitively state that they've successfully swapped them, I would assume they're not compatible.
Apple Watch - Series 3 Batteries
Generally a manufacturer will reuse parts wherever possible to save themselves manufacturing and inventory costs, so having the two models take different part numbers is a good indication they're not interchangeable.
EDIT: Ah, just saw @danj's response; we must have been typing at the same time. He's right that the connectors are probably compatible so you could use the good battery to test the other watch, but ultimately you'll have to buy the right one in order to fit it in.
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crwdns2944067:02crwdne2944067:0
Hey you're not Linus! LinusTechTips. How about changing to fictional person or icon that would be nice!
crwdns2934271:0crwdnd2934271:0 Dan crwdne2934271:0
@danj I changed it to my cat :)
crwdns2934271:0crwdnd2934271:0 Luis Sch. crwdne2934271:0