In your example, you should use "resource." We speak of a "source OF X" and a "resource FOR X," so only "resource" fits here.
The meanings are almost completely different.
A "source" is an origin. It is a place from which something comes or emerges.
A farm is a source of food. English words come from two main sources, Anglo-Saxon and Latin. The source of William Faulkner's book title, "The Sound and the Fury," is a line from Shakespeare.
A "resource" is something available for you to use, if you need it.
Brazil is rich in natural resources, including bauxite, phosphates, uranium, petroleum, and timber. Artisan's Asylum offers a variety of resources for craftsmen, including machine tools, 3D printers, and a woodworking shop. Let me introduce you to Sarah Robbins, who is an excellent resource for all your questions about how we do things here.
In the case of the Internet, it is a "source" of both information and misinformation, and it is a "resource" for anyone with an inquisitive mind..