A discrepancy is a difference between two things that should be the same. I think perhaps your question is better phrased, "the perceived discrepancies between the concepts of time and tense."
Time is a corporeal experience--or a perception of experience--of movement through space and events: You did something when you were five. You do something else now that you are twenty. You will do something different when you are seventy.
Tense is the linguistic construction through which language expresses the experience of movement through space and events. Because of English language linguistic tense inflections (past and present) or constructions (future), I can tell you, "I played pick-up sticks when I was five. I studied half the night when I was twenty. I will swim in the Pacific Ocean when I am seventy."
The perceived discrepancy is that time and tense mean the same thing because both account for past, present, and future. In reality, time is a corporeal experience while tense is a linguistic construction for expressing corporeal experience through the medium of language.