Good question - the two ad types might look similar on the surface, but they work very differently behind the scenes.
Expanded Text Ads (ETAs) are the older format. You write:
3 headlines (only 2 always show)
2 description lines
And that’s it — Google shows the ad exactly as you wrote it, no variations, no mixing.
Responsive Search Ads (RSAs) are more dynamic. You provide:
Up to 15 headlines
Up to 4 descriptions
Google’s system then automatically mixes and matches those headlines and descriptions based on the searcher’s query, device, and behavior to try and show the most relevant combo. Over time, it learns which combinations perform best.
So in short:
ETAs = static → You write the ad, Google shows it as-is
RSAs = dynamic → You give Google building blocks, it assembles ads on the fly
Also worth noting: Google officially sunsetted ETAs in 2022. You can no longer create new ones, but existing ones can still run if they were set up earlier. These days, RSAs are the default — and Google is heavily pushing automation in ad copy.
