On the Lockheed Electra, there was a choice of two prop manufacturers - Aeroproducts (part of GM) or Hamilton Standard (part of United Technology). The Aeroproducts props were square tipped, the Hamilton Standards were rounded. Don't think it made any difference to the airplane although the majority of airlines picked the Aeroproducts prop.
Aeroproducts are now extinct. With the use of composite materials the shape of props has become quite bizarre - notably the Airbus A400 contraprops.