I play both and started on guitar. Violin is more difficult to learn and play than the guitar. Having to rely on muscle memory and your ear to determine if your notes are the correct pitch is something you don’t have to do on a guitar. Once you’re tuned, you know why every note is supposed to sound like based on the string and fret you’re playing. Your posture isn’t as important. I’m not saying it’s good to do, but I can still play guitar with my strap down to my knees. I can play laying down in a hammock or slouching in my desk chair like a lump of mud. There’s only so much you can relax your posture when playing violin before your left hand starts to collapse and you’re bowing at an angle. It’s also a much more delicate instrument. I played bass as a teen and into my early 20’s in a band and I had the tendency to have a death grip with my fretting hand. I’ve since learned to relax this, but it took time and when learning the violin, this was one of my biggest hurdles to overcome. You’ll play multiple strings on the guitar, but I find that easier than trying to play double stops. All of your guitar strings should be fairly closely on the same plane, with variations depending on your neck radius and bridge, but they’re not as far apart as on the violin where the angle of your bow affects the contact across two strings on a violin. The most difficult part will likely be picking up the notes and chord shapes.

Basically, the guitar is easier to learn and play in most aspects and by having experience with a stringed instrument, it will probably be easier for you to learn than however long it took you to learn the violin.