Many lay people would confuse a minor language to a dialect. Probably, the reason behind this is that they confuse a language to a lingua franca (trade language).
In my home country, the Philippines, most people would think that other than the eight major languages; namely, Tagalog, Bisaya/Cebuano, Ilocano, Hiligaynon/Ilonggo, Bikolnon/Bisakol, Waray-waray, Kapampangan, and Pangasinan/Pangasinense, the remaining 167 minority languages are mere dialects of these major ones.
This might help a lay person determine a medium of communication a language. If we speak the language or the lingua franca of the region, where we live in, and we have problem understanding another person, whom we have come in contact with, and we are not prejudicial in any way on the manner that person speaks, consider his language different from yours; hence, a language. If we understand the speaker, despite the differences in pronunciation, accent, intonation, and with some slight intelligibility problem, then, consider his language a dialect.
Dialect is a variation of a particular language. Bisaya in Mindanao, and even the Binol-anon in Bohol island, are dialects of Cebuano/Binisaya in Cebu. Differences in pronunciation, accent, intonation, and a unique verbal production of some letter-sounds or a few extra and unique affixes exist; however, intelligibility between Bisaya (of Mindanao) and Boholano speakers is very high.
Cebuano or Binisaya in Mindanao may pronounced the /l/ in between vowels or may add /ha/ as a suffix to an action word to express exaggeration, example: (katawa = laugh in Cebu) vs. katawaha = laugh in Mindanao), but those Bisaya/Cebuano in Cebu can understand the Bisaya in Mindanao perfectly.
Similarly, the Boholanos/Bol-anons pronounces /y/ as /dz/ (e.g., ayaw (Cebuano of Cebu and Mindanao for 'do not...') vs. adzaw; however, the sentence structure and the words are the same. Henceforth, Bisaya in Bohol is a dialect of Cebuano/Bisaya.
Dialect can be caused by ones social class. This is what we call sociolect. As we, Filipinos, are aware that Tagalog spoken by students in exclusive schools has developed some vocabulary and unique sentence pattern. The differences may be intentional, out of the desire of distinguishing themselves from other Tagalog speakers, or it may have been caused by the school restriction for students to speak in vernacular.
An intentional code-switching in Tagalog, like "kilig to the bones", which originated from co-ed students in prestigious colleges, is an example of a sociolect. Others have caught up to this manner of speaking Tagalog, that we commonly now hear "Taglish", which is a Tagalog with a sprinkles of English words or phrase. Nevertheless, this Tagalog-English mix is also considered linguistically as a Patoi, because it is a non-standard dialect and it is not institutionally supported.
Regiolect or topolect can also cause the existence of dialect. The frequency of interaction and other neighboring languages can result to a development of new words and expressions, and borrowings from other nearby languages. Despite the regional "ala eh" expression of the Batanguenos (of Batangas)and few other lexical (word) differences does not mean that they are not speaking in Tagalog. They are! We distinguish them as Tagalog speaker from Batangas based on some expressions and accents that they have uniquely included in their speech patterns.
I hope this blog helps us not to get confuse on the use of the terms, dialect and language.