Even at 12 megapixels, there are differences in format and compression rates

JPG is about 4 or 5 MB with normal compression

Tiff and RAW can be very large

If you don't need to take very large photos, they don't need to be that large at all

3.0 megapixels, 5.0 megapixels, that's pretty good

There is a lot of difference in the format and compression rate.