Assalam o alaikum. I am going to explain the categories of logical fallacies or defects in reasoning. Fallacies can be categorized into two types.Logical fallacies can be intentional or unintentional. Either I make a mistake or simply I might try to trick you into believing something by using spurious reasoning.Each argument you make is composed of premises and conclusion. Premises are the statements that we use as evidence or reasons to support our conclusion.Formal fallacy:Formal fallacy is same as it sounds like, a defect in the form of an argument.In other words there are certain forms of arguments that are invalid.For example:Statement number 1: If someone is allergic to pickles then he or she doesnt use pickles.Statement number 2: Jane doesnt eat pickles.Now if I conclude that Jane is allergic to pickles. It is wrong. It is not necessarily the case that if Jane doesnt eat pickles so she is allergic. She might not like pickles.So here we can conclude that formal fallacy is a fallacy due to poor form of argument which renders the argument The question in view is not whether a conclusion is true or false, but whether the form of the argument is correct or incorrect valid or invalid.INFORMAL FALLACY:Informal fallacy is a fallacy due to defect in the content or meaning of the content of an argument.So an argument might have true premises in the valid form but still have a false conclusion.Example 1:Statement 1 is : Normally birds can fly.Statement : A penguin is a birdSo conclusion is that penguins can fly.Well, penguins cant fly. So this fallacy arises due to the defect in content, not due to its form.Let me discuss an example that uses equivocation:Example 2:You can use sharp things to cut paper. Ali has a sharp mind therefore you can cut paper with Alis mind.Here I can see that the meaning of the word sharp has been misinterpreted. Only way I can understand this error is to understand the meaning of the words in the argument. But notice here that the Form of the argument is valid so I can use the same form to make a valid argument.So I can conclude my whole discussion in a sentence that if we have to differentiate between both errors of fallacies we can say that formal fallacy is based solely on logical form, and an informal fallacy takes into account the non-logical content of the argument.

Informal fallacy definition is that while it is logically valid, its technical structure (such as use of words) is misleading or unclear which makes the argument unpersuasive.

The absurdity of this argument is more than obvious but the argument is valid as the conclusion follows from the premises. What is more, both premises are true. However, the argument is fallacious due to equivocation. Notice that the same reasoning applied in this argument may does not make it fallacious.

A formal fallacy is contrasted with an informal fallacy, which may have a valid logical form and yet be unsound because one or more premises are false.The concluding statement of an argument may be objectively true, though the argument is formally invalid; or the concluding statement may be objectively false, though the argument is formally valid.A valid argument is one where if the premises are true, the conclusion must be true. An invalid argument, or formal fallacy, is one in which the conclusion does not always follow from the premises. So, for a deductive argument to be valid it must be absolutely impossible for both its premesis to be true and its conclusion to be false.