Root port - The root port is always the LINK directly connected to the root bridge, or the SHORTEST path to the root bridge. It is always on Non-Root Bridge.
Designated port - A designated port is ONE that has been determined as having the best (lowest) cost. A designated port will be marked as a forwarding port. It can be on both Root Bridge & Non Root Bridge. All PORTS of Root Bridge are Designated Port.
Forwarding port - A forwarding port forwards frames.
Blocked port - A blocked port is the port that is used to prevent loops. It only listens to BPDUs. Any port other than Root port & Designated port is a Block Port.