Question

How are lactic and alcoholic fermentation similar?

Answer 1

Lactic and alcholic happens when there is no oxygen.

So, how did it happen?
Recall that in glycolysis of cellular respiration, there is a glucose (6 Carbons) molecule. That glucose molecule is going to be broken down into two pyruvates (3 Carbons). There is no oxygen (also know as anaerobic respiration) so pyruvate is going to be converted into lactate or alcoholic fermentation depending on it's accessibility. I highly suggest you to watch this video if you don't get what I'm talking about:

http://www.bozemanscience.com/cellular-respiration/