Can't see any documentation that says BPDUguard is built in to Portfast, but also don't find Cisco documentation showing BPDUguard always being turned on along with Portfast. (3750 documentation states that per-interface BPDUguard commad can be used to turn on BPDUguard without Portfast, for instance).
Using web-based ocnfigs turn both pon, so I assume both need to be enabled separately, but it's just fuzzy enough in documentaton that I can't tell for sure if Portfast has built-in BPDUguard support.
Any gurus out there?
Both needs to be configured separately, lets discuss them briefly:
When PortFast is enabled (alone on an interface without BPDUGuard) the interface is running STP but it won't transit through listening and learning while coming up and it'll go directly to forwarding - and this would be a source of bridging loops if connected to another switch via this port, STP will eventually solve this loop but not immediately as the port has skipped the listen and learn when coming-up.
As for BPDU Guard, you must consider that BPDU Guard operation depends upon where it is configured. When enabled globally via "spanning-tree portfast bpduguard default" it affects only the ports configured with PortFast, simply if the interface receives a BPDU it err-disable the interface. While if configured on the interface level via " spanning-tree bpduguard enable" it doesn't depend on PortFast being enabled, it can be enabled without PortFast on the interface.