difference options for the same thing

in mono i have noticed that i have multiple words come up on the drop down menu that what i believe do the same thing. can someone please tell me if there is actually any difference.

for example in one line i could use

Camera.main

or

Camera.mainCamera.

or another example i could use

TouchPhase.Began

or

IphoneTouchPhase.Began

is there a difference which i don’t know about??

For both examples you gave the two options do the same thing, but on option is deprecated.