Sometimes difficult. "vascular" headaches are associated with neurologic symptoms, aura, throbbing, unilateral. Tension headache often generalized, worse in pm's, no aura or neurologic sx. Cluster ha tend to be excruciating / lancinating, brief and asssociated with ocular sx. Tension and vascular headache can overlap - more of a spectrum rather than binary division. Response to medications is sometimes helpful.
Migraine? I presume you mean migraine headache. The diagnosis is based on the description you give of the type of pain, any symptoms accompanying the headache, frequency, circumstances and duration. What helps relieve the paincan be a help to diagnosis. Neurological examination is the next step.