The real question is what are there similarities. The airplanes other than the fact that they both have two engines are completely different and do not compete together in the same market.The closest competitor to the A321 that Boeing manufactures is the 737-900. The 737 and the A321 both cary between 175 and 190 people. They both have similar range limitations. About 3000 NM. THe 757-200 has seating for 201 persons and can cary them 4550 miles. You can view all the info on Boeing, and Airbus' websites.