Yoga and tantra share the same goal, but they differ in their approach. Yoga focuses on the body and uses little from the outside world, whereas tantra uses a variety of outside supports, including herbs, that accelerate practice. Panditji explains how he incorporates tantra into his own yoga practice.
You can practice yoga without tantra, though the path is slow and has pitfalls, but tantra without yoga is a disaster, leading to an unhealthy, unbalanced life.