How come it became "that'd be great"? Is it different from "that's great"?
"That'd be great" is an expression that is used to express agreement or excitement about something that is yet to happen. The speaker has used it here to express his willingness to join the bears for pizza. Ex: A: Would you like to come over for dinner tonight? B: That'd be great! "That's great" is more used for something that has already happened, like when a friend shares good news with you. Ex: A: I got a new job! B: That's great!