Process for software evaluation

I work for a company that has a wholly owned subsidiary in another country.

The subsidiary provides the same services and has nearly a mirror image of the the parent company (minus a sales department). Due to cost saving initiatives my team and I are tasked with identifying overlap and elimination of double work.

We have 2 safety departments that each run their own safety software. Each department is biased in their evaluations of each other's software. They only want to keep their own software and only pinpoint the holes in the other's.

We don't have an IT department that can act as a mediator and project facilitator. So, I'm it. I don't have a software background.

I have done some search about software comparison, but reaching out here if anyone has a template or guide for areas that should be covered.

We're talking broad-based items here:
Acquisition cost
Support
Cost of upgrade
Required features
Etc.

I am assuming I could put sub-categories under these. I'm trying to make sure I cover all my bases.

BTW we are talking about comparing off-the-shelf products here.

You need to evaluate the total cost of ownership for both products, over a period of time to show when you will get full ROI on adopting "just one". Include in your estimates license costs to buy the chosen software licenses for non-licensed users currently, training, support, and the cost to convert the non-chosen product's data into the chosen product.

As far as actually choosing the product, once you know the TCO and when you will realize ROI, you can evaluate that against which one actually fully supports the needs of the business.

You may also need to consider where positions may be eliminated when redundancy is removed.