It is VERY different. A writer friend would have discussed it with him and helped him come up with sincere thoughts on why he loved her. The friend would at least know the groom and probably the bride too so they would have insight to explore. It would still be personal.
As someone who has helped several people with their vows, I can assure you that the effort involved is close to 100% pattern matching. Just like AI.
If you used ANY of your own thoughts or your experience and knowledge about them then it was extremely different from AI. If you blindly googled vows and just cut and pasted the first thing you found with no regards for who your friend is, then that would be closer to AI.
Maybe not the first thing, but yeah kind of. AI can pull info from the prompt!