Hello, Thanks for this topic. You can easily make difference of the shop page add to cart button color and the single product page add to cart button color. WooCommerce Beautifier plugin has that option to do it. In the design panel of WooCommerce Beautifier you will see different tabs related to different page. Shop Page and Single Product Page are two of them. You can follow this screenshot here http://prntscr.com/ntfbmt . From those tabs you can change anything and make difference including add to cart button. I hope now it’s clear.
Thanks