When you are performing standing curls you are working your bicep muscles, while a bench press works your pectoralis major and minor, along with your triceps. It's difficult to compare the two exercises because you are working two different muscle groups.
Another possibility is to try and determine what is limiting you in your bench press. I'm not aware of how you train, but generally when someone gets to muscular failure during a bench press, it's their triceps that are actually failing to extend the elbow. Maybe if you tried to strength train your triceps muscles with more intensity, they wouldn't limit you as much during a bench press.
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