The difference between TSG and grammar in context is that grammar is “a description of language structure” a way of understanding language and how it’s used. Grammar is for more understanding and correction. TSG “traditional school grammar” is assumptions about how grammar is best learned, errors are a way of learning and teachers providing constructive assistance is more helpful than error correction worksheets. I have thought of grammar as something that changes because as time passes and people’s writing skills change or improve so does their grammar, everybody’s grammar changes over their lifespan. All the rules are forms of correctness, to make sure the writing follows a specific structure.