Main Differences Between IPF & PF
Kyle Amon,  Page 12
Missing in PF

group and head

level

keep frags

@n rules

bimap (binat)

New in PF

logging in tcpdump binary format only

sets -- Ex. { tcp, udp } and { 127.0.0.0/8, 192.168.0.0/16 }

variable expansion

state modulation ( 'modulate state' keyword )

packet normalization ( 'scrub' keyword )

Different Defaults

ip options