Frame vs Group in Figma

TL;DR:

Use Frames whenever possible.

 Advantages of frames

• You can place a background-color
• You can assign different constraints to different elements (or ignore them by pressing cmd while resizing)
• Manage overflow with clip content
• Assign grids

Actually, there are some specific use cases when the groups come handy, and that's when you want to scale child elements, but not effects, strokes, or type