If there are two employment status records before the earliest Aim start date, only the employment status record closest to the earliest Aim start date will be included in the batch export. The individual export includes all information from the ILR without any collection requirements, which explains the difference.

For example in the below screenshot, the earliest Aim start date is 09/03/2020. Therefore, the employment status record closest to this date, which is 08/03/2020, is included in the batch export.