We have the border tag for images with a border along its sides. There are tags for different border colors and patterns, though only the former implement the border tag.
Also, we have the picture frame tag applied to the frame of picture (object) in an image. I guess it applies to framed inner images as well, e.g. post #3100696, post #1363400.
And, finally, the frame tag but its wiki says
Used when an image appears to be bordered by a photo frame and/or matte.
Can also be used when a photograph depicted within the actual image is held within a frame
The first case could make it to be a certain type of border tag if not the matte. But the second case (and putting the tag to any type of border) turned the tag into the scrapyard of the two tags above.
In additional, there are some unclear tags:
windowboxed - what is the difference from border and color_border?
Tags framed and framed image even don't have wiki.
My own thoughts:
Use the border for solid colors and simple patterns while the inner shape of the border is rectangular.
The picture frame leave as is.
Use frame for images framed by a complex (lace, film, heart) border or detached frame (post #4149385).