# What is the difference between a growth shock and a productivity shock

In a RBC context, what I mean by growth shock is a total factor productivity shock that follows a stochastic trend $$ln(a_t) = ln(a_{t−1}) + \gamma + \epsilon^a_t$$.

I.e. the technology $$a_t$$, has a unit root and grows at an average rate $$\gamma$$

My question is: is this considered as endogenous growth ? If I want to get rid of this method should I replace the growth shock by a productivity shock ? Under what form should this productivity shock be and would it be considered as exogenous growth?