Difference between TGV and OUIGO for train travel in France

Hey all, going to France for my Honeymoon and I need to book a train from Marseille to Paris. It seems as though that route has trains run by both TGV and OUIGO. I’ve done some googling as read that OUIGO is the spirit airlines of train lines, which seems like something to avoid. That being said, what do I need to know before booking this route? Is there a huge difference between the two companies? How about different seat classes? Any recommendations?

Thank you!