Check in and Pop in

Check in verb - Announce one's arrival, e.g. at hotels or airports.

Pop in and check in are semantically related In some cases you can use "Pop in" instead a verb "Check in".

Pop in verb - To make a brief visit.

Check in and pop in are semantically related in advance topic. Sometimes you can use "Check in" instead a verb "Pop in", if it concerns topics such as come into sight, come to a destination.