Nebula and galaxy happen to be two different things present in the universe in which we live. The nebula is directly a Latin word, which means the cloud. Nebula, however, is more than just a cloud. It happens to be a cloud of interstellar dust together with other ionized gases like hydrogen and helium to be precise. On the other hand, a galaxy is a large collection of stars that are held together with the help of gravitational attraction.
A galaxy constitutes the system of stars, star clusters together with interstellar dust. Another difference between these two is that the galaxy is far larger than nebula by a great number of magnitudes. In addition, we can find nebula in a galaxy, whereas a galaxy cannot be contained inside a nebula. Galaxies are classified based on their different sizes, shapes, and brightness into a spiral, elliptical, and irregular galaxies.
Conversely, the nebula is classified into these four types based on their structures: emission nebulae, dark nebulae, hill regions, and supernova remnants. On the other hand, Nvarchar happens to be a column that can store Unicode data at any length. 8-bit coding is the code page that Nvarchar should adhere to.
A significant difference between Varchar and Nvarchar is their sizes, of which the former has a maximum capacity of 8000, while the latter has a maximum size of 4000. This simply means that Varchar's single column can contain up to 8000 characters, while Nvarchar's single column can contain up to 4000 characters at most.