''There is'' is used to express that something or someone exists (at a specific location) ex. There's food in the fridge ( In this sentence the food ''exists'' in the fridge) There's no one outside ( No one ''exists'' outside) ''There is'' also has a plural form ''there are'' ex. There are many people here today (many people ''exist'' here today) ''It is'' is used to either refer to something that you have mentioned earlier in a conversation or to refer that something ''is'' ''It is'' is also used with weather and time. ex. It's very cold today It's Monday (''it'' is Monday) It's my brother ( ''it'' is my brother) It's beautiful (''something'' is beautiful) ''It is'' doesn't have a plural form

Think 'c'est' and 'il y a' . It's: It is the first day of the month It is raining today It is cold There is: There is a cat outside There is snow on the ground There is €20 is my wallet