No. Hair doesn’t grow back differently when you shave it.
Shaving your head is just a temporary hair style. You shave your head and then the hair begins to grow back again in time in the same way it was before you shaved.
At first, you’ll notice your hair is of course spiky and prickly but as it grows, it’ll go back to the same style that you had before assuming you don’t shave it again.
Conversely, shaving your head doesn’t mean your hair will grow back stronger. You’re going to get the same hair back that you had before you shaved it.
Your hair grows from beneath your skin. Your haircutting style doesn’t affect the way it grows back since your hair growth, thickness, volume, color, etc are based on genetics.
If I Shave My Head Will It Grow Back Different? Research Says No
In the past, people believed (incorrectly) that shaving your head would result in hair growing back more healthy and thicker.
In 1928, a medical report entitled Hair Growth and Shaving from Mildred Trotter began to debunk this theory. People keep perpetuating the myth to this day, proving that perception can be a difficult thing to change when people put their mind to it.
In 2007, researchers Rachel C Vreeman and Aaron E Carroll attempted to debunk 7 popular myths, one of them being the concept that Shaving hair causes it to grow back faster, darker, or coarser. From this report which quoted Trotter’s work:
Another common belief is that shaving hair off will cause it to grow back in a darker or coarser form or to grow back faster. It is often reinforced by popular media sources and perhaps by people contemplating the quick appearance of stubble on their own body.
Strong scientific evidence disproves these claims. As early as 1928, a clinical trial showed that shaving had no effect on hair growth. More recent studies confirm that shaving does not affect the thickness or rate of hair regrowth. In addition, shaving removes the dead portion of hair, not the living section lying below the skin’s surface, so it is unlikely to affect the rate or type of growth.
Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2151163/
The research also remarked that shaved hair tends to have a coarse look to it certainly moreso than longer hair. This makes the new hair growing back after a head is shaved appear darker that it used to be. To wit:
Similarly, the new hair has not yet been lightened by the sun or other chemical exposures, resulting in an appearance that seems darker than existing hair.
Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2151163/
Conclusion
If I shave my head will it grow back different? All evidence shows that shaving your head does not change your hair in any way and it will grow back the same as it was before it was shaved.
And shaving your head will not make your hair grow back thicker specifically. That’s another popular myth that just isn’t true.
Shaving your head doesn’t impact how your hair grows back in any way. There is no benefit nor a downside to future hair growth.