One difference is that "hunger" and "starvation" can refer to a single person, or to many people. "Famine" refers to a lack of food that affects many people, usually in an entire geographical area, such as a province, region, or country.

hunger = you want to eat famine = you have very little to eat starvation = you are going to die because you have nothing or not enough to eat Famine will cause hunger and can cause starvation. "hunger" and "famine" can be used for things other than food too.

Hunger has a wide range of meanings. Literally, it means that your stomach is empty enough to be sending you signals to eat. Figuratively, you might hunger for something other than food (e.g. love, recognition, security, etc.) Most humans are hungry sometime during the day. It's not that big a deal if you can get enough food to satisfy your hunger. However, when we talk of "world hunger", we are not talking about everyday hunger but rather the fact that many people in the world don't have enough to eat on a daily basis. "to starve" is to deprive (or be deprived) of food. I might exaggerate and say "I'm starving" when really I'm just hungry. A "starvation diet" is a diet that has so little nutrition as to be under the minimum daily requirement. "starvation" is often applied to large groups of people. "starve" can also be used with things other than food. To extinguish a fire, one can starve it of fuel and/or oxygen. "famine" is a severe insufficiency of food throughout an entire region, usually due to a failure of crops. A famine covers a wide region. In other words, if a few farms have no food, that is not called a famine. If food is scarce and prices are high, that may or may not be a famine. Usually, a scarcity of food is not considered a famine until people are undernourished and starving to death. A famine can cause starvation but the starvation can be alleviated by shipping food in from areas that are unaffected by the famine.

"Hunger" is the name for the physical feeling of needing or wanting food. If I skip lunch, I feel hunger. By extension, it also includes starvation or famine. "Starvation" is the effect on the body of a dangerous insufficiency of food. "There had been no food for a month and he was close to dying from starvation." "Famine" is a lack of food over a wide geographical area. "During the Irish potato famine of the mid-1800s, a million people died of starvation."