Now I'm impressed. How can you tell they are all -400 planes? Please educate me!
Lot's of time studying them!
In the first pic, the the B747s pictured all have winglets. The B747-300 has the stretched upper deck...but no winglets.
The freighter version of the B747-400 does not have the stretched upper deck, but does have winglets. (some have the stretched upper deck, like the aircraft pictured in the second and fifth pic (same aircraft I think), most do not)
Hope this helps!
See the pics below:
#1 is Boeing 747-48EF/SCD HL7436 (cn 23709/671) HL7436 (cn 29170/1305) of Asiana Airlines Cargo. Note the winglets, and that the upper deck looks similar to older -100 and -200 series 747s.
#2 is Boeing 747-422 N128UA / 8128 (cn 30023/1245) of United Airlines. Stretched upper deck and winglets.
#3 is Boeing 747-367 AP-BFX (cn 23709/671) of Pakistan International Airlines. Note the stretched upper deck, but no winglets.
#4 is my personal favorite. Here is Boeing 747-212B N726PA (cn 21048/253) of Pan Am. Standard upper deck, and no winglets. I love the Classics!