if you are changing or pivoting a business plan, because one wasnt successful. The first plan was a failure and you pivoted/changed to a new one. I think both terms are applicable and can be used together.
You can also re-cast the process of founding a startup as searching for a business plan and the goal as discovering information about what the market will bear that nobody else has. In fact, several prominent startup methodologies (Lean Startup & YCombinator's process) recommend doing so. Then you haven't failed at all, because the goal wasn't to execute on the business plan (which you just made up anyway), it was to discover what the actual facts were.
The advantage of this, from a purely utilitarian perspective, is that you don't feel the emotions of shame & disappointment that "failure" usually connotes. And so you can jump into the next idea more quickly, with an open-mind, and pursue it with the same thrill of discovery.
Or maybe the first one wasn't successful yet, or you realize your upside is capped, and you've identified an opportunity that will be potentially more lucrative or have a smaller downside risk. Changing what you're doing doesn't necessarily mean you can't make the original plan work - it might just mean you came up with a better place to put your effort.
One of my favorite business stories is that of the Nintendo Playing Card Company of Kyoto, whose CEO came to the US to visit the US Playing Card Company. He realized that even if he captured the entire world market for playing cards (this is before MtG) he still wouldn't have a very big business, and set out to find something better.
The advantage of this, from a purely utilitarian perspective, is that you don't feel the emotions of shame & disappointment that "failure" usually connotes. And so you can jump into the next idea more quickly, with an open-mind, and pursue it with the same thrill of discovery.