Translation:Spring, summer, fall, winter are seasons of the year.
Although they are both correct, "Hè" is usually not used when it comes together with the other seasons, when it is with the other reasons: "Xuân" , "Thu" , "Đông" which are Hán-Việt words , it should be in it's Hán-Việt form: "Hạ". Generally , you will never hear any Vietnamese says "Xuân,Hè,Thu,Đông" both in the South and the North.
Generally, yes, but it is perfectly acceptable and I've looked around and it's not uncommon to see it used. When we speak of Hán-Việt pairings/words you need to realise that it's more complicated than simply having the standardised form used. For instance, we would say tín dụng but never tin dụng for 信用, yet, we would always say thông tin but never thông tín for 通信 even though 信 only has 1 reading in the Chinese languages. It is quite common to see pairings like "Thời trang Xuân Hè" and we even see examples like "Chiến dịch Xuân-Hè".