Both Internal links and Inbound links are a valuable part of SEO strategy. These are both essential links to have on your website however they are different and its important to know the differences.
Inbound links are links that come from other websites into your website, these are known by Google as a referral. Each referral you get Google counts as a point in favour of your website. The practice of acquiring these types of links is known as link building.
However you must be careful as Google can determine the context of the link. For example if you get an inbound link from a website that has nothing to do with your business type, Google will count this as a point against your website instead of in favor of it. This Change came about when Google implemented their Hummingbird Algorithm which saw a huge change in the way website are ranked and how users can search.
The goal of Google and other search engines is to provide internet users with the most relevant information possible, so you need to make sure that all outbound links on your website send your visitors to destinations relevant to your content and your business type.
Internal links are links from the content on your websites internal pages. They are links on one page of a website that point to a different page of the same website. E.g. Notice within the questions on this website, there are links to associated questions and answers on different pages of this website.
This is to create a user flow throughout site. Websites that have poor Internal links will likely have a high Bounce rate and low average time spent on the site by users. As the users are not being prompted as to where to go next, they will just leave.
Internal link structure is important, they should be set up in a way that makes it easy for a user to navigate through a website. Internal links are a form of a call to action.
Weather you are working on your inbound or internal link building strategy, remember to keep asking yourself, how will this benefit my user?