MB is larger. There are 1024 KB in a MB. MB are bigger, just like GB are bigger than MB. Just think of Kilo being small, Mega being large, and Giga being huge, and then there is TB, but I won't get into that right now.
The word explicit means clear and fully expressed. If something is explicit, there is no question as to what it means, no hidden connotations and no room for misunderstanding. If a fact is explicit in a reading comprehension passage, it is stated outright. For example, if the first sentence of a story is It was a dark and stormy night, that is an explicit fact.
A company's explicit costs can include employee wages, payments made to purchase raw materials, business rent/mortgage payments and fees related to purchasing manufacturing equipment. Of these explicit costs, a business considers rent/mortgage payments and the cost of purchasing manufacturing equipment as fixed costs. Variable explicit costs include employee wages because the cost of paying workers increases as the business ramps up production. Equipment maintenance costs and utility payments for retail store locations can also increase as a business raises production levels.