I'm confused as to what Google Map API I will implement to my website regarding this plot.
1 - My admin user will set the address of a place on the google map (probably in textboxes) 2 - The users can view the place set by the admin and has already a marker in that specific place.
What are the differences between the v2 and v3?
Thanks for helping.
To use API V2 you need a key and now it's impossible to get one because API V2 has been officially deprecated as of May 19, 2010, just like Marcelo said as a comment of your question.
You will need to use Api V3. Check the Google Maps JavaScript API v3 for more details.