stroman 
If you imagine SEO as a bowl of soup (our favorite metaphor), your website is the soup.
The on-page SEO is all the ingredients in your soup… content, keywords, meta tags, descriptions, internal linking, etc… basically, everything you can do on your site.
And off-page SEO is the fire from the stove top heating up the soup… basically, everything you do outside of your website (like link building).
Here’s a link to a great resource that puts it all together.
As SEO becomes ever more sophisticated, it’s always a good idea to keep up on the latest techniques. Thanks for the share! Definitely upvoting this one.