Bastion Grey vs Light Gray

How close are they?

ΔE 20.7, loose: different enough that you should pick on purpose. Light Gray is a little lighter, more muted than Bastion Grey.

Can I use Light Gray instead of Bastion Grey?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Light Gray is a little lighter, more muted than Bastion Grey.

Can I use Bastion Grey instead of Light Gray?

The same difference applies the other way round: Bastion Grey is a little darker, more saturated.

ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.