Inside forward, he doesn't possess the vision or crossing ability to play as a winger. As a striker he'd play as an advanced forward on the shoulder of the defender, looking to make runs in behind
When Walcott plays on the right he plays as a Winger/Attack as he focuses on getting in behind the defence and looks to shoot or cross depending on his position. When Walcott plays up front now he is more of a Advanced Forward due to his tendency to get in behind and move into channels to create space for the likes of Ozil and Sanchez. Hope this helps!