For starters the online degree is usually looked at by potential employers as a "quick" degree...something where you didnt have the intense sessions where you might have a state college. You also only end up with an associates degree in some cases and not a true bachlors degree.
Now the exception to the rule is obtaining your degree online from a state institution. Here in AZ we have a whole "online campus" through the various state universities where you can earn a full bachlors degree in a variety of subjects and you get a piece of paper just like any student who attended the actual campus would have.
Accrediation also comes into play. A state program usually is accrediated by some governing body whereas the univ of phoenix type of degree usually isnt accrediated by the most recognized bodies or possibly even at all. For example:
http://www.distance.nau.edu/programs...line_only=True - listing of all online degrees offered by Northern Arizona university and their levels
It really depends on the subject matter you are going into though. for nursing and clerical you end up with an associates and it doesnt get you in too many doors. For the computer degrees its prettymuch a course on how to pass the A+ and MCSE and possible Cisco exams.