What is the difference between bool and Boolean types in C#?

bool is an alias for System.Boolean just as int is an alias for System.Int32.
C# Type.NET Framework Type

bool System.Boolean

byte System.Byte

sbyte  System.SByte

char System.Char

decimal System.Decimal

double System.Double

float System.Single

int System.Int32

uint System.UInt32

long System.Int64

ulong System.UInt64

object System.Object

short System.Int16

ushort System.UInt16

string System.String