The oak that comes with kits is a many and varied thing, especially from RJ Spagnols kits.
I don't have as much experience with Winexpert kits, and have not made the Choc Rasp port, but oak powder is often included in kits. The fine nature means that there is a LOT of surface area, and the oak's goodies can be extracted quickly. Mentally compare the powder to a lump of oak the size of a sugar cube (that's about the size of an oak cube). Oak chips are in between in size, although closer to the powder.
Steve