You can identify the core using the following:
#define ATTINY_CORE - Attiny Core
These are used to identify features:
#define USE_SOFTWARE_SERIAL (0 = hardware serial, 1 = software serial
#define USE_SOFTWARE_SPI (not defined if hardware spi present)
#define HAVE_ADC (1 = has ADC functions)
The following identify board variants (various cores have used both styles of defines, so both are provided here to maximize compatibility):
#define ATTINYX4 1
#define __AVR_ATtinyX4__
#define ATTINYX5 1
#define __AVR_ATtinyX5__
#define ATTINYX61 1
#define __AVR_ATtinyX61__
#define ATTINYX7 1
#define __AVR_ATtinyX7__
#define ATTINYX313 1
#define __AVR_ATtinyX313__
//no backwards compatibility options since no previously existing cores used the other convention.
#define __AVR_ATtinyX41__
#define __AVR_ATtiny1634__
#define __AVR_ATtiny828__