Can both "guess" and "hunch" be used interchangeably or is there a minute difference? I know it doesn't apply to the phrase 'I guess', but generally when do you use "hunch"?
Guesses are more assertive than hunches. A hunch can be seen as a hint or feeling and is something that typically indicates a suspected outcome or result:
I have a hunch that they are lying.
My hunch suggests otherwise.
I am only working on hunches.
The conveyed message is that there isn't much rhyme or reason behind a hunch. The only backing is... just that it exists. You very rarely have control over hunches and once you can point toward why you have a hunch it starts becoming less of a hunch and more of a guess.
A guess can drift from potshots to educated guesses and are considered more challengeable. Where a hunch simply describes your feelings or thoughts, a guess is expected to have some meat behind it. Asking why of a guess is expected. Asking why of a hunch is pretty pointless.
I guess that they are lying.
I guess otherwise.
I am only working on guesses.
The scale does continue from there, but the range of guess is very broad and context is important:
If you had to guess, what is the population of Mexico?
I don't know the answer, but I can guess.
Are you guessing?
This is an educated guess.
I have no idea, but my guess is five.
I can guess.
Beyond guess are words like answer:
This is my answer.
What is the answer?
Is that your final answer?
A "hunch" is typically associated with someone having an intuitive, "gut feeling" about something.
I have a hunch that the plants were moved by an animal.
A "guess" is usually more generic and hints at less intuition or feeling and a tiny bit more cognition.
Can you guess who was at the party?
For me the differentiation is that one can precede the other in only one instance, meaning a hunch can precede a guess, but a guess would not precede a hunch.