meta data tag names

[reader]

Having a little trouble penetrating the peculiar language of meta data tags.
A few questions:

What is the difference between 'Composit images size' and 'Full Image size' (in this case Sony)
Which tag contains the information about size in MB?

Regex searches of the tags inside the layout dialog, with 'size', 'dimen', 'mb', '\<mb\>', '\bmb\b'... have not found the desired tag.
Or perhaps I just wore out on scrolling thru what seem to be arbitray names.

[Mario]

What is the difference between 'Composit images size' and 'Full Image size' (in this case Sony)Which tag contains the information about size in MB?
Which tag contains the information about size in MB?

That's a question for Sony, or Phil from ExifTool. The tag names come from ExifTool. For a list of all tag names, and some descriptions, look here:

http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/index.html

Usually a Composite image is an embedded preview or a composite image created my merging all layers in Photoshop. The units may be pixel or bytes, I can't say. IMatch displays the information as delivered by ExifTool.

Which file format are you using? Which camera? Maybe I have a similar image here.

[joel23]

Having a little trouble penetrating the peculiar language of meta data tags.
A few questions:

What is the difference between 'Composit images size' and 'Full Image size' (in this case Sony)
Which tag contains the information about size in MB?
[...]

I believe none. Those are dimensions, in pixel. Use File Size instead.