Before you set out to evaluate a source and decide if it's useful for your research needs, you need to know what kind of information you have. Knowing more about it can help you evaluate it properly. Is it a popular source like a newspaper article written by a journalist? Or is it a scholarly source with original research that was written and reviewed by experts?
Format refers to how information is packaged.
Some formats are better than others for your purpose.
Examples of Information Formats
Source refers to the actual information content. All sources require some level of evaluation. Knowing what kind of source you have will help you evaluate it properly.
There are a range of source types, but the two ends are popular and scholarly.