Winds via RTE DATA will be for the entire route. If no altitudes are specified, it will give winds for the initial cruise altitude and any Step altitudes enroute.
Winds via VNAV DESCENT page are for the arrival terminal area only, for a preprogrammed set of altitudes. No route winds will be given.
Depending on the provider of the winds and the firmware load, VNAV DESCENT winds MAY be sent along with the RTE DATA winds request. Even if they are sent, they have to be loaded separately. RTE DATA winds must be executed, VNAV DESCENT winds are not executed. If you fail to load the VNAV DESCENT winds after they are sent via the RTE DATA request, further wind requests will not get any response until you LOAD the pending VNAV DESCENT FORECAST request.