What is the difference between「唐人」and「漢人」in Cantonese?
漢人 only refers to people of the Han ethnic group


It is correct、漢民族 is the major ethnic group in China, but 漢人 do not equal 中國人

唐 and  漢 are both great dynasty in Chinese history


Cantonese speakers prefer 唐 over 漢 as the representative word for "Chinese" . We have terms like 唐人，唐餐，唐裝，唐話，唐字 in Cantonese
Mandarin speakers prefer 漢 over 唐 as the representative word for "Chinese" . We have terms like 漢文，漢字，漢語，漢化 in Mandarin



  Does「唐人」in Cantonese mean exactly the same thing as「漢人」


No, 「唐人」in Cantonese mean exactly 「華人」 or 「中國人」


Both Cantonese and Mandarin speakers use「華人」 or 「中國人」for "Chinese people"


It is believed that 華夏 period culture was the beginning of Chinese culture

華夏最初是指史前黃河流域中下游一带分佈的若干部落或政治共同體，这些部落被后世视为漢文化及中华文明的起源之一

《左傳》“裔不謀夏，夷不亂華”一語，華、夏同義反復，華即是夏 (夏即是華)