Could somebody throw enough light on the difference between Adverb and Adverbial?
They can be used interchangeably. If you see both in the same text, then 'adverb' will probably refer only to those single-word references to time, manner, etc, many of which end in -ly (never, slowly, very, clumsily), while 'adverbial' will refer to longer phrases and clauses that serve the same purpose (under the table, when I sat down to eat, etc.)