They are different lossless image formats. What is called "raw" is quite a few different formats from different manufacturers, and they contain lossless image data from the camera sensor without significant postprocessing. They usually need some postprocessing to look "good". A "bitmap" is just pixel data, not a file format, but .bmp is a file format, which does support some compression, and usually won't contain raw camera sensor data but something ready to be displayed on a screen.

No an expert here but RAW is the data generated by the sensor and requires some heavy processing before you can show it on screen. A bitmap is an image format (assuming you mean the BMP files).

A big difference is bit depth. BMP normally is 8bits per pixel per channel (colour). RAW is often more bits (say 10 or 12 or even more). This means you can adjust lighting without introducing banding and so on.

most importantly a RAW file hasn't been demosaiced, ie instead of pixels of colors, it's a grid of scalar sensor measurements that, depending on the pattern (eg Bayer) each represent either red, green or blue intensity. since we only know one for each position in the image, the other two have to be interpolated (which is demosaicing)