Are cultural/mainstream generations = / = historical/sociological generations?

[Cocoa_Puff]

For me, it's this:

Cultural Range
Cultural generations tend to be around 15-18 years in length and are more based on mainstream pop culture trends.

My cultural ranges for generations:

• GI: 1901-1924 or 1901-1927
  
• Silents: 1928-1945 or 1925-1942
  
• Baby Boomers: 1946-1964 or 1943-1960
  
• Gen X: 1965-1980 or 1961-1980
  
• Millennials: 1981-1997; could end between 1996 and 1998
  
• Gen Z: 1998-2014; could start between 1997 and 1999
  
• "Gen Alpha": 2015+
  

Historical Range
Historical/demographic/sociological generations are longer in length and are generally 20-25 years in length. They are based on having four generations in 80-100 year saecula.

My historical ranges for generations:

• GI: 1901-1927 or 1910-1927 (18-year theory); 1901-1924 could work too but I still see 1925-1927 as GIs for good reason
  
• Silents: 1928-1945; possibly 1925-1945
  
• Baby Boomers: 1946-1963 (18-year theory) or 1946-1964; could possibly end in 1962 or even 1965
  
• Gen X: 1964-1981 (18-year theory) or 1965-1981; 1964-1982 or 1965-1982 could work too; could start between 1963-1966 or end between 1980-1982
  
• Millennials/Civics: 1982-1999 (18-year theory) or 1982-2000; probably could also be 1982-2001 or 1982-2002; could start between 1981-1983
  
• Homelanders/New Artists: 2000-2017 (18-year theory) or 2001-2018/2019; probably could also be 2002-2019 or 2003-2021
  
• Neo-Prophets: 2018+ or 2020+; could also be 2022+