Nearly and almost are essentially the same. They mean that somebody or
something came close to doing something… but did not do it.
For example, if Jane is running in a race and came in second place, just a couple of
seconds behind the winner, then you could say:
▶️ Jane almost won the race.
▶️ = Jane nearly won the race.
If your computer battery only has 8% power left:
▶️ The battery is almost dead.
▶️ The battery is nearly dead.
The words almost and nearly describe being very close to some limit
(0% power) or action (winning the race).
The word mostly means generally, usually, or more than half. If it is “mostly
cloudy,” then it means the sky is more than half covered with clouds. Mostly
describes a proportion, the greater part.
If there are 20 people in an English class and 17 are from South America but 3 are
from Asia, then “the students are mostly from South America.”
There is also a difference between “most of” and “almost all.” “Most of” means
more than 50%, and “almost all” means close to 100%.
▶️ If 70% of the senators voted to approve a new law, then most of them voted
in favor of it.
▶️ If 97% of the senators voted to approve a new law, then almost all of them
voted in favor of it.