"someone who has a passing interest in your site, looking to find some information or browsing around for comparison purposes."
"someone with a longer term association or affiliation who potentially logs into the site, or gains knowledge of the structure and becomes expert in achieving their tasks."
“Users with an affiliation to a site (web application) are likely to become impatient if their progress is impeded, and casual visitors to a site (web application or content site) are more likely to become bored if the content is not engaging or visually appealing.”