<A> is the ANCHOR or HYPERLINK element. With the HREF attribute, it is used to link to other files or sites. Clicking or choosing the anchor will link to the file or site. With the NAME attribute, it is the destination of a HYPERLINK.
The IMG element displays an inline image in the document. That is the document is not replaced by the image on the computer screen. Instead the image is part of the document. Most all browsers can display images stored in the GIF format developed by Compuserve. These are identified with an .GIF extension in thier file name.