Underground Comix are known for using different prices, covers (art or color variations) and/or interior content to distinguish between printings.
Here both printings have 0.50 USD cover price.
1st print has blue & pink bottom text boxes, blue beer cans, guy has orange hair sitting on bluish green towel.
2nd print has white & orange bottom text boxes, orange beer cans, guy has brown hair and sitting on green/yellow towel.
— Description from Comic Vine community (comicvine.gamespot.com · https://comicvine.gamespot.com/facts-o-life-sex-education-funnies/4050-28929/).
