I agree to an extent, but it's not because of whether they are maternal or paternal grandparents, but more about the people they are.

For example, I will leave my children with my father for a few hours without a second thought, but I won't leave them with my father in law for more than 10 minutes. My dad is ridiculously over protective to the point of being annoying to the kids, but it means that I know they will always be safe. My FIL isn't & the one time he was left alone with both kids, he left my then 15month old DD near three steps that lead to the garage which was open to the road. She fell down the steps & had a nasty head injury.

Both gradmothers are treated equally.

My two are the first grandchildren on both sides so there's no-one else for them to treat differently IYKWIM.