With Ember’s EM260 images, the filenames usually reflect the EZSP serial style used. Depending on the release of EmberZNet you’re using, the firmware filenames may differ according to the significant pieces of functionality that are present/missing from the EM260 network coprocessor [NCP] images.
So, for example, in EmberZNet 3.3.0, there is only one SPI EZSP firmware image: em260-spi-with-standalone-bootloader.hex . This supports all features mentioned below, including debug capability and radio+SPI bootloader support.