(Not a teacher)
The past tense just refers to language that refers to events occuring in the past. This can be done using various tenses:
Simple past - I walked home.
Past progressive - I was walking home.
Present perfect simple - Note that this tense indicates an action that occured in the past which affected the future - I have walked home. Now I can rest.
Past perfect simple - I had walked home.
Present perfect progressive - Note that this indicates a past event that has continued into the present, and may continue into the future - I have been walking.
Past perfect progressive - This describes an event in the past with emphasis on how long the event lasted, often using 'since' and 'for' - I had been walking for 5 hours.
So, these are all past tense. Simple past is just one way of indicating past tense in English.
Wait for others' responses, as I'm not a teacher and am relatively new to grammar.