Below is some difference between Eureka 3670G and 3684F:
Eureka 3670G vs 3684F
The Eureka 3684F comes with HEPA filter traps tiny dust, pet dander, and other small particles, makes the exhaust air cleaner.
The Eureka 3670G does not include a HEPA filter.
Pet Hair Attachment:
The Eureka 3684F comes with a PET Power Paw to pick up pet hair from rugs, carpeted stairs, upholstery, etc.
The Eureka 3670G does not have this PET Power Paw.
The Eureka 3670G is cheaper.
The Eureka 3684F is priced at $149.99 on eureka.com.
The Eureka 3670G is priced at $79.99.
( Prices checked on 03-20-2013)
The Eureka 3684F is purple and black.
The Eureka 3670G is in yellow and black.
If you know any other difference between these 2 Eureka canister vacuum cleaners, please share below to help others make a right buying decision.