They have the exact same meaning, except for the fact that "have a go" is more used by British speakers, whereas "have a try" is more American. "Try" is the general verb, so it wouldn't necessarily be interchangeable, the meaning of your sentences conveys something more related to "give it a shot"/"give it a chance". Oh, and remember that verbs end in -ing when they follow a preposition. I hope it helps! :)