First, the object is different.
1 and long:long are instance objects in the C# base library System.Int64.
2.int 64: int64 is an object defined in the C# basic library System.Int64.
Second, the statement is different.
1 and long:long adopt the declaration method of value types in C#.
2.Int 64: int 64 adopts the declaration method of reference types in C#.
Third, the accuracy is different.
1 and long:long are long integer data types, and data conversion to int64 will not lose precision.
2.Int 64: int 64 is an integer data type, and the data converted into long will lose precision.