type of C#

Question

So I am planning to use C# for coding in Unity and I see that there is some things that are different from each other. For example here they ask for me to write this:

Console.WriteLine("Hello!");

while in Unity I would write something like this:

Debug.Log("Hello");

Is there something that is different from both them or am I missing something. Also when here when they write down voids they state it as:

static void Main(string[] args)
{}
And Unity does:

Publc/private void()
{}

So if someone would be able to help me that would be great