Of course distinguishing this from a sunk cost fallacy is largely in the eye of the beholder.
Well, no. Because you are assuming ("eye of the beholder") that they are indistinguishable.
Sunk cost fallacy is a fallacy, which means that it is, by definition, irrational (or, if you prefer, it is a part of the cognitive biases we all have). All it means is that people suck at understanding future benefits, and overvalue past costs.
On the other hand, path dependency matters even assuming a world with perfect information and rational actors.
Now, if this is too theoretical for you, I'll give you an easy example:
You are watching Is it Cake? on Netflix. After 15 minutes, you realize that the show is terrible.
Sunk Cost Fallacy: I've already invested 15 minutes, I might as well keep watching.
Path Dependency: No effect, since there is no real cost to switching to something better (or if you are a real stickler, the de minimis cost of ending the show and putting something else on will be outweighed by the benefit you will receive from watching anything other than Is it Cake?).