In general, a port of entry is a place where one may lawfully enter a country. It typically has border security staff and facilities to check passports and visas and to inspect luggage to assure that
A port of entry at Shir Khan Bandar in northern Afghanistan near the Tajikistan border.
A border checkpoint is a location on an international border where travelers or goods are inspected and allowed passage through. Authorization often is required to enter a country through its borders.
Port of entry
…travelers who are not carrying goods over the customs limits; others may only cross the border at a designated border crossing during its opening times. Border checkpoint Border control…
Sultan Iskandar Building in Johor Bahru, Malaysia Singapore border
Woodlands Checkpoint, Malaysia Singapore border
Italian-Swiss border post – since Switzerland joined the Schengen Area in 2008, this checkpoint is solely for customs formalities