Restrictive clauses limit the meaning of the subject they refer to, while non-restrictive clauses provide additional information about the subject without limiting its meaning. A restrictive clause is essential to identify which room is being referred to, as in "The room on the first floor is the largest one," while a non-restrictive clause adds extra details, like calling a room "your favorite," without that information being essential to understand which room is meant.

1. CLAUSES: RESTRICTIVE AND NON-
RESTRICTIVE

2.  A restrictive clause limits the meaning of a
preceding subject.
Example:
The room on the first floor is the largest
one.
The subject “room” is being restricted by the
clause “on the first floor”.
WHAT IS A RESTRICTIVE CLAUSE

3.  A non-restrictive clause tell us something
about the preceding subject, but doesn’t limit
it’s meaning.
Example:
The room upstairs, which is your favourite, is
being painted.
The “room upstairs” isn’t restricted by being
my favourite room.
WHAT IS A NON-RESTRICTIVE CLAUSE