Hi Lily
Correct term is simply self or cross pollination.
Whether self-pollinating the same flower with its own pollen or a different flower on the same plant makes little odds as they will both carry a similar random mix of genes. There are no 'exact same types' unless they are cloned from the same plant. e.g a named hybrid. The term P. caerulea for example describes a species that is really a quite diverse group with variable foliage and flowers.
By convention when describing cross pollination put the female flower first and the male pollen provider second. e.g. P. caerulea ÂConstance Eliott à P.gritensis = P. caerulea ÂConstance Eliott flower with P.
gritensis pollen.
For more info see link below.
Myles

Here is a link that might be useful: Hybridizing

Thanks, Myles.

So, based on my cateogisation above, there's no difference between 1 & 2. If a flower can't self-pollinate, it won't work pollinating with another flower on the same plant.

But what about 3? Does it mean a flower that can't self-pollinate, can still be pollinated with another flower on a different plant that is a clone? Why so?

re 3...if a flower cannot self pollinate it cannot be pollinated by a flower from a clone- that is a genetically identical plant grown from a cutting of the same parent plant. For an in depth look at how pollination works see the link below.

Here is a link that might be useful: Passiflora pollen adhesion