sense-cents, tense-tents, mince-mints, prince-prints etc.

Are these homonyms or is there a difference between these word pairs

All homonyms

The word "homonym" is imprecise, because it can mean either "homophone" or "homograph".

The words you gave may or may not be homophones, depending on the speaker.

They are obviously not homographs.

Okay then, are these word pairs homonyms. Are ''tense'' and ''tents'' homonyms. Some people say they are but my dictionary lists [tens] for ''tense'' and [tents] for ''tents''.

In connected casual speech for many native speakers, these words are homophones. In very careful speech and in principle, they are pronounced differently. It's difficult to pronounce [nts] rapidly, so often it is shortened to [ns] in casual or rapid speech. There are many, many other examples of such shortcuts, not only in English but in most other languages.

I was just wondering because truespel actually respells ''fence'' as ''fents''. Shouldn't it become ''fens''?

sense-cents
mince-mints
tense-tents
prince-prints
patients-patience

Your pairs are homophones, even in careful, deliberate speech.

Unless the 'n' (followed by [s]) is fully nasalised, (as in French, not in English) the result will always be a "nts". If the 's' or 'c' is softened to a [z], then the result will be a "ndz".

ie: "fens" [fenz] is effectively "fendz"
but,
sense [sens] is effectively sents.

The "connection" between 'n' and 's' Mxsmanic was inferring happens for these pairs because they are of one syllable, but disconnection could occur where a syllable follows "ns", eg: in the word "sensitive" -> sen-sitive. Even then, there's often a hint of unavoidable "ts" inherent, else interruption of flow would create division, implying separate words. It would sound unnatural and perhaps startling to hear this kind of complete separation in "sense" -> sen-s.

I do not pronounce them the same.

When I pronounce tents, scents, etc., I have a slight stop for the 't'.
This stop is absent in tense, sense, etc.

That is, when I say tents I put my tounge against my hard palate to stop my breath, then glide it down to my teeth to make the s. When I say tense I move the tounge directly to my teeth, with no stop.

This is even more obvious if I use the words 'tentses' and 'tenses'.
Of course tentses isn't a real word, but the addition of the second
syllable makes the stop for the t even more unmistakeable.

Where are you from D?

I compare it to the pronuncation of "flower" ~ flau-w.. : you can't evade the 'w' sound unless you make a complete stop before it.

I'm from Pennsylvania. My wife from upstate New York also pronounces
tents and tense differently. She claims that she 'tries to say the t' in tents.

Another way of describing the difference is that I don't completely nasalize
the n in tense but I do fully nasalize it in tents, which make a stop in the
word.

I've never heard "ents" pronounced with a stop or without the 't' sound.

* Correction : Unless the 'n' ... is fully nasalised -> ONLY nasalised.

I pronounce ''want'' to rhyme with ''punt''. I pronounce ''wont'' (meaning 'likely to' or 'tending to') to rhyme with ''guant''. I do not pronounce ''punt'' and ''guant'' to rhyme.