Ii am really new to this so if I am going to learn one before the other and using a Rocket Theme (because I bought three licenses) which one should I use for my Website?
Will be mostly Ecommerce (Woocommerce) but will also have galleries and company info etc.
Everyone will have their own opinion as to which CMS is better suited for your needs.
In my opinion, WordPress is a great choice if you want your site to have a blog with regularly-updated content. Joomla is a great choice if you understand Joomla and want a solid CMS with more inherent control on the back end. WordPress is a lot more user friendly after development, making it a great choice if you plan to hand the keys over to someone with less development experience after the build.
Joomla is more developer friendly (so I hear from our dev team). For end users, there is a bit more of a learning curve. Quite a lot more, in my experience.
RocketTheme's themes (especially in Gantry 5) are the same on any platform.
Ryan Matthew Pierson / Technical Writer / Buda, TX USA