Consider the following sentences:
‘The guests were entertained by Arpana.’
‘Arpana entertained the guests’.
Do you see any difference in the two sentences? Are you able to grasp what the sentences are saying? It appears from both the sentences that a girl called Arpana entertained guests. Apparently, there is no loss of meaning in the sentences. Each of the sentences is giving the same meaning. The only difference one can make out is that Arpana is at the end of the first sentence and at the beginning of the second, and the word ‘by’ is missing from the second sentence, as is the word ‘were’. Actually, what you are witnessing is the sentences in PASSIVE voice and in ACTIVE voice.