you should use both seo onpage and seo offpage

On Page Activities:-

Meta Description
Title Tag
Keyword
Content
Google Analytics
Google Webmaster

I also think On-Page and On-Site SEO are the same

On page SEO is-
1.Title tag
2. Keyword research
3. Meta Description
4. Headers tag
5. Quality Content
6. Sitemaps
7. URL Structure
Off page SEO is-
SBM, forum posting, classified, content sharing, blog commeting, blog posting, profile creation and many more.

On-page and Onsite-pages are same,

On page Techniques are very important to improve our website ranking.
-Title tag
-Meta description
-Meta keywords
-Heading tags, H1, H2, H3...
-Robot.txt
-Sitemaps
-URL structure
-Internal Linking

I think both are same,

On Page Techniques are,
Title tag
Meta Description
Headers tag
Sitemaps
URL structure
Robots.txt
Internal linking..

On page seo means optimizing your website and making changes on title, meta tags, site structure, site content, solving canonicalization problem, managing robots.txt etc.

Off page optimization means optimizing your web presence which involves backlink building and social media promotion.

on page is the best techniques to promote website in google. you should follow all the steps of On page.

1. Useful, high quality, relevant content

2. Update Your Content Regularly

3. Metadata - Title, Description and Keyword

4. Have a link-worthy site

5. Use alt tags

6. Page load speed

7. Image optimization

8. Header tags (h1 to h6)

9. Outbound links

10. Broken links

On-page SEO have some technique to improve our site on Search engine marketing.
Meta tag description,
title tag
robots.txt
xml sitemap
if you are done proper in onpage SEO that will helpful to promote your site on Search engine

On Page SEO :
Title tag
Meta tag
Content Optimization
Image Optimization
Google Analytics
Google Webmaster

Off Page SEO:

Directory Submission
Article Submission
Search Engine Submission
Video Submission
Image Sharing
Social Media Opttmization etc..

I Think both of Same, it helps to ranking our website in the search Engines.