opportet vs debeo

[Territus Latinae]

In the same lesson I learned about oportet, oportere, oportuit, 2, intr - it behooves, it is necessary, and debeo, 2, tr. - ought, owe. The book listed 'ought' as a primary definition for debeo and an alternate translation for 'it is necessary/it behooves' for opporto, but it has been using them interchangeably as far as I can tell in translation of 'ought'. Is there a difference between the two definitions, and is one better than the other? I'm doing Henle Latin.

Thank you.

 

[Adrian]

in short:
1) oportet - it must be ; it ought - obligation from duty, becomingness (obligation of morality and honor); oportet denotes objectively, the moral claim which is made upon any man
OPORTET officium significat, rationem, iustam causam.

http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.04.0059:entry=oportet

2) debeo - I have to, I ought to, I owe something (I have a debt to pay)
Si volent grati esse, debebunt Pompeium hortari, ut mihi sit amicus. Civis talis, qualis et prudentissimus et fortuna optima esse debet.
DEBET qui morali obligatione obstrictus est ad aliquid faciendum
http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.04.0059:entry=debeo

Source : John Philips Potter, An Essay on the means of discovering the senses of Words

 

[Territus Latinae]

That helps. Thank you.