Wet beriberi refers to congestive heart failure
Dry beriberi refers to peripheral neuropathy
Wernicke's encephalopathy refers to the triad of ophthalmoplegia, ataxia, and confusion
Korsakoff syndrome refers to memory loss/psychosis
(You don't need to really know the distinction between these two tbh, just know that they stem from the same etiology)
ALL of these are manifestations of thiamine deficiency.
As you know, alcoholics are particularly prone to having thiamine deficiency due to poor diets and interference of thiamine absorption due to alcoholic gastritis. Likewise, alcoholics with thiamine deficiency can manifest as any of the above clinical pictures. Indeed, Wernicke-Korsakoff tends to be much more closely associated with alcoholism, though EtOH use is not necessary for diagnosis. I would presume that alcoholics are more prone to the CNS manifestations of thiamine deficiency due to a superimposed alcoholic encephalopathy, though this is just my conjecture.
Hope this helps