What is the difference between at least one head and at most one head in...

Difference between at least one head and at most one head in probability.
At most one head means number of heads in probability is $0$or $1$. At least one head means the number of head is greater than or equal to $1$.Example: If two coins are tossed together then the probability of getting at least one head , atmost one head is:
The possible outcomes are:
$\left(HT,HH,TT,TH\right)$
So,$\left(HT,HH,TH\right)$
At the very least, one head implies the quantity of head is one or greater $\left(HT,TH,HH\right)$
Atmost one head means the number of head is one or zero. That is $\left(HT,TT,TH\right)$
Therefore, at most one head means number of heads in probability favourable outcomes is $0$or $1$. and at least one head means the number of head is greater than or equal to $1$.