Hello Jimmy,

standard etherchannel load balancing uses an exor of IP SA and IP DA to decide out what member link to send the packet.

For STP the bundle is single logical link in forwarding state for all Vlans.

vlan priority based load-balancing can be used on L2 trunks in parallel:

instead of building an etherchannel the links are left indipendent, but STP costs are manipulated differently on different links for different subsets of Vlans.

In this way each link carries only the traffic of a specified subset of vlans for which it is in STP forwarding state.

Hope to help

Giuseppe