Both words mean the same thing, i.e. that something can be set on fire. The reason for the confusion comes from people thinking that the prefix in- of inflammable is the Latin negative prefix in-...
'If it be' is in the subjunctive mood, whereas 'if it is' is in the indicative mood. They convey the same meaning, but the indicative would generally be used in informal everyday speech or writing,...
Combustible means it will burn but it's difficult to ignite. Wood is combustible. Flammable items will burn and they're easy to ignite. Gasoline is flammable. "Inflammable" is an old term that means...