The age difference between you and your great grandfather is 74 years (88 - 14 = 74). The age difference between your great grandfather and your great-great-grandfather is 21 years (109 - 88 = 21).
In terms of the age difference between you and your great grandfather, it's not common to have such a significant generational gap, but it's not entirely unheard of either. Many factors can contribute to age differences in families, such as when individuals have children at different ages or if there are several generations between siblings.
As for the age difference between your great grandfather and great-great-grandfather, 21 years is not an unusual age gap for that level of generational distance.
Keep in mind that what is considered "normal" in terms of age differences between generations can vary widely between families and cultures. Ultimately, the most important thing is to cherish the time you have with your family members and the opportunity to learn from their experiences and stories, regardless of the age difference.