Can anybody give me the differences between Americano and Espresso because I am quite confused.
An espresso is a shot of coffee produced by forcing hot water at high pressure through coffee grounds. Often, the espresso is the base shot of coffee from which other coffee drinks are prepared, although it is also quite common to enjoy it on its own.
An americano is a coffee drink made by pouring one espresso and then adding hot water on top of it. This hot water weakens the coffee a little and mitigates some bitter notes. It is also consequently a larger drink and retains its heat for longer.
As Ivan mentions in the comments, you may also be interested in the long black. It's a little like a reverse americano, where the espresso shot is pulled over hot water. This retains more of the crema than an americano does.