Dear Meenu,
Our learned friend Saswat has given a correct answer to your query but a little bit briefly. Hence I feel that for the sake of better understanding it needs to be elaborated with reference to the definition of the term " industrial dispute " as defined u/s 2(k) of the Industrial Disputes Act,1947.
If you critically analyse the term, you will find that it comprises of three parts.
The first part defines a dispute crisply as a difference.
The second part mentions the parties to the dispute; the dispute can be between workmen and employers or between workmen and workmen or between employers and employers.
The third part specifies the subject-matter of such a dispute between the parties thus mentioned. It can be connected with the employment or non-employment or the terms of employment or with the conditions of labor of any person. Here, the word " any person " refers to not all and sundry but only that person in whom the the parties have a community of interest.
Applying the above principles, we can conclude that even though the said trade union issue is a dispute between workmen and workmen, the subject-matter is totally different. Therefore, it is not an industrial dispute to be resolved under the provisions of the ID Act,1947 but only a civil dispute to be resolved by a Civil Court.