책방 and 서점 (not 사점) are almost same. 서점 is like 書店 which means "書 Writing & 店 Store" and 책방 is like 冊房 which means "冊 Book & 房 Room" For the bookstore, 서점이 more commonly used. you can still say 책방 though. and If I add, You can say you have a 책방 in your house. but you don't say you have a 서점 in your house unless you are selling but Mostly you say you have a 서재 in your house.

"책방 and 서점" ("사점" is wrong) They mean the same thing, "bookstore". 책방(冊房): 책(book) + 방(room, small store) 서점(書店): 서(book) + 점(store) 책방 is an old word with a feel of "small and informal" bookstore. Nowadays 서점 is more prevalent because it sounds more general and modern.