According to the Champion plug web site they are both bantam height. But a different bantam height.
I ran into this and found that the plug looked different where the wire connected and sealed t the plug and that was the only difference.
cj6y and cj7y are identical
CJ7Y works with no issues.
Champion CJ7Y Champion RCJ6Y Autolite 2974 Bosch WSR6F Denso W22MP-U NGK BPMR7A
autolite 2974 or xst2974 (irridium) champion rcj7y, cj7y ngk bpmr7a
Champion CJ7Y or NKG BPM7A or Megafire SE-Y7C or Bosh WS7F
In place of the JENN FENG 9295-331501, I am successfully using a NGK (7021) BPM6A sparkplug; Which is cross referenced to two Champion plugs CHAMPION CJ8Y or CJ7Y