TGA is a raster graphic format. It was originally created by Truevision Inc. for graphics cards has its own production in 1984, but later became popular on a variety of platforms, especially in the field of video editing, animation. Format supports color depths 1-32 bits per pixel. There is support for alpha channels, compression RLE.
BMP is format for storing bitmap images. In this format, you can only save bitmaps monolayer. For each pixel in different files may come different number of bits. The latest versions of the BMP has the ability to control color. In particular, you can specify the endpoints perform gamma correction and embed color profiles ICC.