In CS, it is not the title that is tied to the pay, but the scheme and its corresponding job grade. An Assistant Director at MTI is a fresh grad at MX Grade 13 with its equivalent fresh grade Grade 13 pay. An Assistant Director in another Ministry say MHA could be someone with about 7 to 10 years of working experience at MX Grade 11 so the pay is naturally higher with bigger responsibilities.

Similarly, a Senior Assistant Director can be anybody with just 1 to 2 years of experience to maybe 10 to 15 years. So you need to know what is the scheme and the job grade in order to know the expected salary range.

Just to put things in context, the Permanent Secretary is the highest ranking civil servant in a Ministry. He or she is usually at Grade 6 to 8. Just a secretary you'd say...? Fancy title really don't mean much in CS. I have heard of people with just "Senior Specialist" or "Senior Analyst" titles earning at least 10k to 15k...