It's different. According to the public information of the query, 3m is 3mb, which is different from 300mb. Mb is the abbreviation of English MByte, which is the storage unit in the computer. Pronunciation is "megabyte". MB and MB (note the case of the letter B) are often mistaken for the same meaning. In fact, MByte means "megabyte" and Mbit means "megabit".