Both vowels are pronounced the same. It means the difference between them is purely orthographic. Students do not like them because of the spelling errors they cause (and because of the bad marks as a consequence).
The character ó is named “u” kreskowane (more often) or “o” kreskowane in Polish.
The vowel u (spelt u or ó) is short (like all Polish vowels), but it resembles long English u in Luke. It sounds like Spanish or Italian u or like French ou but it is less intensive.
Here are some examples:
tu ‘here’, but ‘shoe, boot’ , Bóg ‘God’ ([buk]), Bug (name of a river in the eastern part of Poland), buk – type of tree, mój ‘my, mine’, kogut ‘cock, rooster’, usta ‘mouth’, wnuk ‘grandson’.
Have you noticed that Bóg, Bug, buk are homophones? It means the three words are pronounced in the same way, as [buk].
The sounds ł and u/ó like being together. In those instances you should read them very carefully. Try to say: łuk ‘bow, curve, arc, arch’, stół ‘table’, muł ‘mule’ and also muł ‘slime, mud, silt, sludge’, dług ‘debt, obligation’ ([dłuk]), długo ‘long, for a long time’, słój ‘jar, pot’, główka ‘small head’ (read [głufka], diminutive to głowa ‘head’), tułów ‘trunk, torso’.
The “ó” is used if the different forms of the word switch between “o” and “ó”, for example please compare “sól” (salt) and “solny” (of salt),
If on the other hand the word, in all its forms, keeps the letter “u”, like “drut” (wire) and “druciany” (of wire) then we write it always a “u”.
To make things easier, the kids in school learn that “uje się nie kreskuje” (no apostrophe if the word ends on “uje”), thus learning a general rule that words like “pracuje” (he works) are always to be spelled with “u”.
Although there are some general principles you can follow when spelling, unfortunately, there is a number of exceptions that you only must learn by heart.
Do następnego razu… (Till next time…)