(JPEG) file is a lossy raster file format that compresses an image to make the file smaller. JPEG files are some of the most popular and widely used image formats in the world. Photographers can shoot in JPEG mode, while graphic designers, illustrators, and other creatives can edit their work in them. A RAW file contains all the uncompressed and unprocessed image data captured by the sensors of a digital camera or scanner. They’re also a type of raster file format, but one that maintains lossless quality. RAW files are not images they’re just large files filled with the image data as it was captured. 

Generally, a RAW file will be between two and six times larger than a JPEG file. so therefor RAW files are bigger than jpeg because they contain a much greater amount of image data. A JPEG image is essentially all that data compressed down into a smaller file size that’s easier to share. and yes you can change the raw files. the only way to change it is that you have to Open the photos in RAW format, e.g. in Photoshop. Go to ‘File’ and choose ‘Save As’ and select from the list ‘. jpg’ (it might appear as JPEG).