For all real world purposes - it's the exact same thing. The only difference the ester makes is how fast the drug is released into the blood stream and how frequently you need to do your injections. Testosterone is testosterone.
Both test e and test cyp are long estered forms of testosterone that should be injected twice per week.
test e - half life 10.5days
test cyp - half life 7 days
Just pick up whichever is cheaper. They are literally interchange in every way.