The Red Mason Bee (Osmia bicornis) is about the same body size as the European Honeybee (Apis mellifera).
Females are larger than males.
Males have gray-white hairs on their faces while females have black facial hair.
In addition, males have long antenna while females have short antenna.
These bees are not aggressive.

A male. Nature Reserve Schlangenberg, Breinigerberg, North-Rhine Westphalia, Germany, 3 May 2022