Clinical depression means that you meet the criteria for a depressive episode
Manic depression = bipolar and means that in addition to meeting the criteria for a depressive episode you have had at least 1 episode of mania (bipolar I) or hypomania (bipolar II)
People with bipolar still get clinically depressed... but bipolar is treated differently to "unipolar" or depression without (hypo)mania. A lot of us are diagnosed as depressed for many years before our manias are noticed especially with bipolar II. The good news is that now you can get meds that will work for what is actually wrong with you...
good luck with your journey!!!