New Year's Day of ancient is Lunar New Year(the first day of the first lunar month), until 1914, China goverment renname it to Spring Festival, so there are same things in New Year's Day of ancient and Spring Festival of modern.
New Year's Day of modern means the first day of the first gregorian calendar month. Lunar calendar is popular in china before 1912, which is offical calendar, China goverment start using gregorian calendar in 1912, and naming the first day of the first gregorian calendar month as New Year's Day. The first day of the first lunar month has not a official name between 1912 and 1914, when 1914 China goverment renname Lunar New Year to The Spring Festival.
China now, lunar and gregorian calendar all are exists. New Year's Day means first day of the first gregorian calendar month, Spring Festival as know as Lunar New Year means the first day of the first lunar month, they are different festivals, and both of them have holidays.