There are many correct answers to this question, as there are many differences between -er and -or. The similarity they offer is that they are both suffixes. People use -er and -or when they want to express something. -Er is used when it is necessary to show that a person is a doer of an action.
An example is with the word cook. A person who cooks for a living would be a cooker. The word cooker could also be used to refer to a device that cooks, such as a slow cooker. -Or can also be used for a person who is doing the action. For example, to act is an action. A person who acts is an actor.
Er and -or are known as suffixes that are typically used by people when they want to express something. Some people use -er when they want to show that the person is the doer of the action that is being created, for example, the word bank.
The one who works at the bank will be called a banker. Other verbs can be changed into a noun with the addition of the suffix -er. The suffix -or can also be used to show the person who does the action. For example, when you say the word “animator,” this means that the person is someone who has made it possible to make the objects animated.
Suffixes are one or more letters, words which are added at the end of a word to modify the word's meaning. -Or and -er are examples of suffixes which when added to another word can change or modify the meaning of the word completely. For example, when you add -or to words like advise, protect, direct, it becomes advisor, protector and director. Also when you add -er to words like play, it becomes player. This shows it has changed the meaning of the word 'play' which is a verb to 'player' which is a noun.
Another difference is that, both -or and -er are used to differentiate between American English and British English. There are so many words in America English which are not acceptable in British English. For example, advise is a verb, but advisor can only be acceptable in America English if it is written as adviser, while adviser can only be acceptable in British English if it is written as advisor.
Er and -Or are both suffixes that can be used to make the noun easier to understand. For example, if the root word is “advise,” you can change the e to -or and make it advisory. This means that this is a person that can provide the advice that you are looking for. These suffixes have one similarity.
They are often used to show who is the doer of the actions that are being described. For example, you may say “designer.” Design is the root word, and you have added -er to show that the noun is someone who designs different items.