The basic difference between artilceship and industrial training is change in the role.
In articleship training you work riguorously under an employer and work as article assistant. He/She is also called as auditor and audit different corporate bodies like companies etc. One audits the work of the auditee,
Whereas, in case of industrial training, one joins as industrial trainee in any of the companies approved by the institute, prepares all the details and get the work audited by the auditors.
The difference between articleship and industrial training is change of the position of the chair.
So far as your question is concerned that Industrial training with Indian Oil Company will add any value to your carrier ?? the answer is a lot.
There is high probable chance that the Company in which you have done your industrial training might absorb you. The Company need not spend its resources (either in the form of money or time) for training as the industrial trainee must have gathered required experience and knowledge of the workings of the Company.
You can check institute website for other details.
Further, as you said that time would be short for exam preparation, then you should utilise the time period which you are having before that one month period. Utilise the time a lot, read/study the topic in which u are dealing in the Company. Utilise the time of conveyance (office to residence and vice versa - read ebooks, study materials on auditing standards, accounting standards, Q and Ans on various topics /case laws/ amendments etc. in this period.