Why is the difference in boiling point so much greater between methanol and methane than it is between 1 decanol and decane? So any data sheet will tell you; 

Group 1: methane boils at: -164 deg C
         methanol boils at: 65 deg C 


Group 2: decane boils at: 174 deg C
         1-decanol boils at 229 deg C 


that being said; why is the difference in boiling point so much greater between methanol and methane than it is between 1 decanol and decane ?

As well is there anything else other than difference in non-polarity and IMF's that contribute to differences between molecules in individual groups (i.e. between methane and methanol; between decane and 1-decanol)
The difference in boiling point, between methanol and methane on one hand and between 1-decanol and decane on the other hand, is primary due to the presence of hydrogen bonds (HB) in methanol and 1-decanol and not in methane and decane. The density of these intermolecular forces (HB) is higher in methanol than in 1-decanol (In 1-decanol, for every ten atoms of carbon there's one possibility to have HB. While in methanol for every atom of carbon there's one  possibility to have HB.