A tending grunt — a buck dogging a hot doe — is rapid-fire and rough, often repeated every few seconds. A contact grunt is single, soft, and low. A snort-wheeze is a separate aggressive vocalization usually reserved for buck-on-buck challenges.
For calling, mimicking a tending grunt during the chasing phase pulls cruising bucks toward the source — they assume another buck has located a doe. Use sparingly and stop calling once a buck commits. See state rut date pages to know when chasing is most likely on your ground.