Both your original comment and seanfranco's response are gross over-simplifications. Aside from the fact that Dublin, with its widespread suburbs, has half a dozen distinct accents (including some that are noticeably generational - people who grew up in Dublin in the 1950's do not sound like people who grew up in Dublin in the 2000s) that reflect geographical, social and educational differences, a lot of people living in Dublin are only first generation Dubliners - they, or their parents, were not born in Dublin, and their accents, especially the informal bits like "plural you", reflect this.
Spoken Hiberno-English tends to differentiate between singular and plural "you". The expression of that differentiation takes different forms in different places. The long "yee" of Cork might be written "ye", but it sounds quite different from the "yeh" sound in other parts of the country, and, while "youse" is often attributed to Dublin, it is well mixed with the "yiz" version that is heard throughout Leinster and into Connacht. "You're" can be either "yee-er", "yisser" or "yous-er", whereas "your" is more likely to be just "yeer" or just not make the singular/plural distinction at all.
I'm sure I could spend an hour listening to recordings of Imelda May on YouTube to find examples to back this up, but I'm not going to......
Is it a distinction in English? When your kid tells you that he needs the new XBox, or a sales assistant asks if you need some help, they probably mean "want", rather than "need". Is there a difference between a sign that says "Staff wanted" and a sign that says "Staff needed"?. How about "I need to go to the shop - do you want anything?".
There's a difference between the nouns "a need" and "a want", but in day-to-day speech, the verbs "to want" and "to need" are often used interchangeably.
So the only way to tell whether the above sentence is "You want a duck" versus "You need a duck" is by context? If you had to choose between the tá or the teataíonn form to say that someone wanted something, would one form be more appropriate or is it just a matter of preference?
Since one of the meanings of “want” is “need”, it would be better to contrast the possible meanings of “You want a duck” as “You desire a duck” vs. “You need a duck”. Yes, context is the main differentiator, although a particular Irish dialect could prefer one meaning over the other (in which case the dialect would be the context). To avoid ambiguity, one could use e.g. Tá fonn lachan agat for “You desire a duck”, and Tá lacha de dhíth ort for “You need a duck”.
I have too. I've been reviewing the same lessons over and over again since January because I still haven't mastered them (sections 1 and 2). I don't dare tey to learn more if I can't get this stuff into my head. If I go forward I'll never really learn it. So I review and review and review forever. This streak is over 500 days long, for heaven's sake! When will I master just this far?
Neither teastaíonn nor uaibh mean "want".
teastaíonn means "is wanted", and ó is used to specify who the subject of the verb (lacha, in this exercise) is wanted by.
teastaíonn lacha ó Phól - "a duck is wanted by Paul"/"Paul wants a duck"
teastaíonn lacha uaim - "a duck is wanted by me"/"I want a duck"
teastaíonn lacha uaidh - "a duck is wanted by him"/"he wants a duck"
teastaíonn lacha uaibh - "a duck is wanted by you (guys)"/"you (guys) want a duck"
More colloquial than old-fashioned. It's the equivalent of the "y'all" or "you all" used in parts of the southern US, and it is one of a number of different 2nd person plural forms fairly widely used in informal speech in Ireland. And just to confuse matters further, they don't pronounce "ye" the same way in Cork as they do in Mayo, and you're more likely to hear "yiz" in the East.