I didn't understand the difference so I google'd it:
TLDR: Cyano B12 is the cheap stuff and Methyl B12 is good
Enter Google AI:
Production : CyanoB12 is synthetic, while methylB12 is naturally occurring.
Body use : The body can convert synthetic forms of vitamin B12 into natural ones. After absorption, the methyl group is removed from methylB12, and the body must re-form it to make it usable.
Supplements : CyanoB12 is more commonly used in supplements because it's less expensive than other forms of vitamin B12.
Foods : MethylB12 is found in foods like fish, meat, eggs, and milk
Health benefits : Both forms of vitamin B12 can help with conditions like B12 deficiency, pernicious anemia, ALS, and neuropathic pain. MethylB12 may also help with sleep quality and circadian rhythm.
Bioavailability : Some research suggests that methylB12 is more bioavailable than cyanoB12, while other research suggests that there's no difference in absorption or bioavailability between the two forms.