GTA V aka Grand Theft Auto V is a Action-Adventure Game Developed and Published by Rockstar Games.
GTA V (Offline)
This version of GTA specially for single player. GTA 5 offline have regular campaign mission and side missions as Michael De Santa, Trevor Philips or Franklin Clinton.
After completing those missions your game will end like a movie with a story. And then after that you can freely roam in the game and do whatever you like but there will be no mission available later. But you will find stranger and freaks by passing by certain locations.
GTA V Online
GTA V online is a multiplayer game. You will get vast missions on GTA online. You can customize your player, cars, their looks etc. and can choose your group or team through which you invite players to play a designated mission at Los Santos as a co-op.
You can also purchase properties, guns etc. and be the president of your team.
In it you either just messing around on the map or doing missions (ranges from racing and clearing waves of cops to large heists which are more similar to the single player campaign) to earn money so you can buy better cars and weapons.
And the game frequently update their new contents and Jobs.
And Their Is More The Most Exciting Roleplay.