In most cases, you can expect advertising networks such as Google Adwords to track more conversions than ATLAS, however ATLAS can be both Javascript and Pixel image based.  However, there will be cases where ATLAS could track more conversions than Google Advwords – how? – simple, if the user(s) switches off Javascript and makes sales on a site then you can expect, if the action tag is pixel based, that ATLAS will pick up the extra conversions.