why did the Indian Constitution makers not mention the word federal instead of Union of state under article 1 of the constitution

Article 1 describes India, that is, Bharat as a ?Union of States? rather than a ?Federation of States?. The country is described as ?Union? although its Constitution is federal in structure. According to Dr B R Ambedkar, the phrase ?Union of States? has been preferred to ?Federation of States? for two reasons: one, the Indian Federation is not the result of an agreement among the states like the American Federation; and two, the states have no right to secede from the federation.

The cardboard shows me how it was how figures of speech

the cardboard shows me how it was figure of speech