What is the difference between drift and trend in a time series?

Question

I am analyzing a time series using the unit root test. I am stuck in that I do not understand the difference between trend and drift in the time series. Is it correct to say that trend is a feature of a time series, whose average changes over time and that drift is a feature of a time series, whose variance changes over time?

Answer 1

Drift is an intercept(static) component in a time series.

c being the drift(intercept) component here.

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Trend is represented as a time variant component δt, observe the below equation.

Trend being a time variant increase or decreases over time, so your statement of changing average is true.

I hope this clears your doubt between the two!