Granularity and Grain

Granularity:-
Granularity is nothing but a least level of information we can get from a table.
For example let us consider time dimension.

Time Dim
Year
Month
Date
time

from this time dimension the least level of information what we can get is based on time
Grain:-
Grain is association between fact table and dimension table.
For the least level of dimension what are the association in the fact?? – is nothing but grain.
Example :-
For the same time dimension as above. The fact entries are
Bookings Fact
Time key
Territory key
Region key
#Bookings
$ Bookings Actual
$ Bookings Target
Here for time_dim.time_id(Pk)=bookins_fact.time_key.both fact and dimensions are at least level ie,time.
Ex:- lets have one more
fact Target_actual_f
region key
quarter key
$ Mgmt_rev_target
$ Mgmt_rev_actual
Here, the fact contains data per region level and quarter level which is said Granularity.
For the quarter and region key how is the association in fact is said Grain