is int is strut

Answer 1

No, int is a keyword. It is used to declare/create variables as being able to store integer values.

struct is used to encapsulate (or store in short) variables, methods, etc.
For example :

struct Car
//Car is a struct, inside the '{}' is what it stores/encapsulate
{
int BatteryPower;
//BatteryPower is a variable, int is the keyword being used to declare/create it
}

Answer 2

int is a keyword which aliases the type System.Int32 which is a struct.