something comes upとsomething has come upの違い

This is not a piece of advice to you I'm talking to myself for my practice of writing skills.
1): something comes up
2): something has come up
1):the tense of this sentence is the simple present tense
2):the tense of this sentence is the present perfect tense
1):some thing comes up during the present time.
2):some thing has come up already at present time.