I'm having trouble differentiating between the two past tenses.
Is the use of the two past tenses in Polish similar to the differences between preterit/imperfect in Spanish? If there are any differences what are they?
Besides knowing when to use which, I am having a hard time distinguishing between which one I am seeing when presented with a word or which one I am hearing when I hear a word. What morphemes should I be listening/watching for that distinguish them?
There is only one past tense in Polish if you don't count the rarely used pluperfect. Maybe you mean the two different aspects which can also occur in the past tense?
In that case, a verb in the past can take the perfective aspect (aspekt dokonay) and the imperfective aspect (aspekt niedokonany).
Here is the post that should explain question 1 for you.
As to distinguishing them, I would say it's a matter of remembering what the stems of the two aspect forms look like, when learning new verbs. Unfortunately there is no rule about how you can transform one form into the other, so you should learn both.
You can also check out this site: http://mowicpopolsku.com/polish-grammar/tenses/
I hope this helps a little... Polish verbs are so confusing. I figure it's just going to take some time to learn all the different forms :)
there is only one past tense but 2 aspects of verbs: when the activity is finished or not finished. Ja przeczytałem - I have read/I finished reading Ja czytałem - I was reading (for some time but not finished)
Ty obejrzałeś - you have watched/ you watched/ finished watching Ty oglądałeś - you were watching