Mod is NOT Hippie. The two styles coexisted but they were polar extremes.
The people who are saying, “eh, it’s just casual clothes, jeans and tshirts” are only partially right.
Jeans & pants were often snug, hip-hugger (low-cut) and usually bell-bottom, the bigger the bell the better. What are called “flare” jeans in this year’s current fashion start to approach the idea, but don’t come close. If the jeans were embroidered, so much the better. Tie-dye, yes. Beads, peace sign jewelry. Macrame & crochet – belts, vests, headbands, etc. Vests of leather, suede, or fabric, often worn by men without a shirt underneath. Floral and paisley fabrics, even for men’s shirts. Pants with wide vertical stripes, plaids, or patterns. You can also get into the ethnic wear, especially African & Indian – dashiki, Nehru jackets, those pullover shirts that have a mandarin collar and split placket in front. Mutton chop sideburns, beards, mustaches on the men. Unkempt hair on men and women (although some women sported the long, stick-straight look). Afros on people of all ethnicities.
But, as someone who was a child in that era, I will say that a major component of true hippie style – not just what your average teen would purchase at Sears – was sloppy, ragged, dirty, smelly. The true hippie did not care about personal hygiene as much as one might have wished.
Take a look at the movie Hair, for example. Also pictures of The Beatles in the late '60s / early 70’s.