Bracts look much like scales, but bracts occur wherever a flower's pedicel attaches to the peduncle. Stated another way, flower buds are produced in the bract axil. Sometimes a flower bud does not continue its growth beyond very early stages. When this happens the dormant or aborted flower bud may be so small it remains hidden by the bract, and you may mistake its bract for a scale. But remember, scales never occur on a Utricularia inflorescence above the lowermost flower.
Bracteoles are usually narrower than bracts but are otherwise similar.
The evolutionary forces of nature are thrifty, and organs are rarely retained if they are not useful. I recently severed the tip of a U. prehensilis scape by accident, and in a few weeks a new scape branch grew from behind a peduncle scale. So at least in this case the scale was protecting a region of meristem tissue. This tissue was activated into growth by the damage the scape suffered, and the plant flowered successfully. Similarly, I think a function of bracts and bracteoles is to protect embryonic flower buds from damage.