Answer:

Butterfly

Difference : butterflies wings are much longer than bees

difference: butterflies have brighter colors than bees

difference :butterflies are totally harmless

Bees

Difference: bees have larger nest than butterflies

difference : bees will sting when they perceive  threats on their hives

difference: beees gather nectar and pollen while butterflies only gather nectar

Similarities: Both are insects.

                   Both have two pairs of wings

                   Both are pollinators