What is the difference between /ʊ/ and /ʌ/ in British English?

/ʌ/ cut, hut, bun, nothing, love, enough, flood, does

/ʊ/ put, soot, foot, good, look, cook

To me the ʌ is a more short, low front (unrounded?) vowel, but the vowel /ʊ/ which sounds like "uh" is a short, high back (rounded?) vowel but this difference is only minor that you could probably swap each sound when speaking and get away with it.

For example, pronouncing cut as /kʊt/ "kuht", instead of the short /kʌt/ "kut". I can do this with the other words too: hut, bun, nothing, love etc.

Edit: I'm talking about British English phonology, not American English...

For example in AmE, you can say soot in 2 ways (sʊt and su:t ?), Merriam Webster:

\ ˈsu̇t , ˈsət, ˈsüt \

The sounds of /ʌ/ and /ʊ/ are only moderately similar from a strictly phonetic point of view. However, in the context of phonology, you might feel like the difference is "[so] minor that you could probably swap each sound when speaking and get away with it" for a couple of reasons:

• the contrast has a low "functional load": in standard English, /ʊ/ is a rare sound, and there are only a few pairs of words, such as buck and book, that are distinguished solely by the use of /ʌ/ vs /ʊ/. (In other dialects, the same pair of words can be distinguished differently by the use of /ʊ/ vs /uː/.)

• In some fairly widespread British English dialects, /ʌ/ is not normally used and words that have /ʌ/ in standard English instead have /ʊ/.