What is a rosebud rivet and what is correct for my 1970 c10?

[Harrison.]

I've got a '70 C10 that's got rivets that look just like the picture below (I know the VIN tag below is for a later model truck than mine). My dad has a '72 that has identical rivets and I've always assumed they were correct for my truck. I've seen threads pop up discussing the correct rivets talking about rosette rivets and I assumed that they were talking about what my truck has.


However, recently I read a thread where a pic was posted of a '70 VIN plate and it had hexagon shaped rivets like below. I've since searched eBay and found various pics of trucks that also had these rivets.


I'm in the middle of a frame off on my truck and my VIN matches the frame in both spots so I have no doubts that they belong together, but it's got me scratching my head. Can anyone shed some light for me?