On-page SEO activities are used to generate website traffic through significant changes on web pages. Activities like improving page load time, website structure, title tag, inter-linking, meta tags, quality articles, etc are some examples of On-Page Optimization activities.
Off-page SEO activities include tasks done outside of your website but on the search engine to improve visibility, credibility, domain authority, etc. Generating relevant backlinks, social media marketing, guest blog posts, Quora marketing, etc are some off-page activities.