Difference between BinaryWriter and BinaryFormatter.Serialize?

BinaryWriter is used to write primitive types in binary to a stream and supports writing strings in a specific encoding. BinaryFromatter is responsible for serializing an entire object or graph of connected objects into binary format. So, I suppose you can say BinaryWriter is a much more elementary form of something like BinaryFormatter.

I got this information here: BinaryWriter & BinaryFormatter

BinaryWriter and BinaryFormatter are two different thing.

BinaryFormatter is used for serialization. It helps you to map a C# object to a binary representation which you can write to a file, a network stream etc.

But BinaryWriter does not help you map the C# object to binary data. It just gives you the ability to write binary data (as the name implies). So you give it primitive types like an int, it converts it into binary and write it. After writing when you need reading it you have to use a BinaryReader and you must know somehow that you have to read an int. So you have to serialize your data somehow yourself.

You can say BinaryFormatter uses BinaryWriter to be able to write binary data but it does a lot of other jobs to automatically serialize and deserialize your object.