We can make a Linguistic distinction between languages and dialects
The difference between a language and a dialect can be explained using several linguistic guidelines as well as recent scientific evidence.
A linguistic explanation can best distinguish a language from a dialect using several metrics. The first of these is mutual intelligibility, which means that two speakers of different linguistic varieties can understand each other without training. Two different linguistic varieties are considered to be separate languages if they are not mutually intelligible, and they are dialects otherwise. Another method is shared vocabulary--that is, multiple linguistic varieties using the same word for the same object. If two linguistic varieties have a very high percentage of overlapping vocabulary, they are typically dialects of the same language and not separate languages. Recent research also suggests that humans have a cognitive distinction between dialects and languages, so each is processed slightly differently in the brain. A 2018 study from the University of Dundee tested whether switching from one dialect to another is the same as a multilingual person code-switching between languages, and it appears that these two phenomena are different processes. This type of study could be expanded in the future with more language varieties in order to decide whether they are languages or dialects.
Many linguists agree that a linguistic explanation alone cannot adequately differentiate between languages and dialects because there are too many exceptions to these "rules." For one, the principle of mutual intelligibility cannot account for why speakers of Bosnian, Serbian, and Croatian can understand each other perfectly despite these being three separate languages. Also, simply because two linguistic varieties have a high degree of shared vocabulary does not mean that they are dialects of the same language because this does not take borrowed vocabulary into account. There are many Arabic loanwords in Farsi, but these are two different languages belonging to two completely unrelated language families. Also, even two dialects of the same language can have extremely different vocabulary due to differences in speakers' education or social group.
Rejecting the premises
More on the debate on languages and dialects: https://www.theatlantic.com/international/archive/2016/01/difference-between-language-dialect/424704/ More on the debate on languages and dialects: https://www.babbel.com/en/magazine/accents-and-dialects An exploration of English dialectology: https://www.google.com/books/edition/American_English/vPdgBgAAQBAJ?hl=en&gbpv=1&dq=wolfram+and+schilling+2016&printsec=frontcover