What is ICO?

Windows icons, and a container rather than an image - one file holds the same icon at several sizes, so Windows can pick the right one for a title bar or a desktop. It tops out at 256x256 and supports transparency, which is what stops an icon looking like a sticker.

What is TIFF?

The format print shops, scanners and archives run on. Lossless, capable of holding several images in one file, and old enough that everything in that world reads it. Files are large, which nobody in print has ever minded.