They do basically the same thing. The Gripen is better suited to Ukraine’s needs; it’s cheaper to fly, able to operate with less infrastructure, and able to fly farther out from home. However, there just aren’t that many of them in the world compared to the F-16. The F-16 has been produced way more, and there are countries like Norway that just replaced all of their F-16s anyway. There are other differences in each one obviously, but I’m no expert on it. Both are designed to do largely the same job, and the specifics of performance for each will depend heavily on exactly which version of each plane is handed over seeing as both have had literally decades of development and upgrades.

I imagine that, much like the situation with tanks, you’ll just see that different Ukrainian units will operate different equipment depending on what is available. Whoever is running their logistics must have an unbelievable coffee budget, but if that means more tanks and jets operating then they’ll make it work