In botany|lang=en terms the difference between flower and bractlet

is that flower is (botany) a reproductive structure in angiosperms (flowering plants), often conspicuously colourful and typically including sepals, petals, and either or both stamens and/or a pistil while bractlet is (botany) a bract on the stalk of a single flower, which is itself on a main stalk that supports several flowers.

As nouns the difference between flower and bractlet

is that flower is a colorful, conspicuous structure associated with angiosperms, frequently scented and attracting various insects, and which may or may not be used for sexual reproduction or flower can be something that flows, such as a river while bractlet is (botany) a bract on the stalk of a single flower, which is itself on a main stalk that supports several flowers.

As a verb flower

is to put forth blooms.