Function difference() but for specific fields?

you may try cdtdifference() function available in 'CDT Diff Utilities' custom plugin.

https://community.appian.com/b/appmarket/posts/cdt-diff-utilities

Might it will helps ,

load(
local!array1: {
{
id: 1,
name: "bob"
},
{
id: 2,
name: "bill"
},
{
id:3,
name: "mary"
}
},
local!array2: {
{
id: 1,
name: "joe"
},
{
id: 2,
name: "john"
},
{
id: 4,
name: "john"
}
},
a!forEach(
local!array1,
difference(
tointeger(
index(
fv!item,
"id",
{}
)
),
tointeger(
index(
local!array2,
fv!index,
"id",
{}
)
)
)
)
)

You could try creating a couple of new arrays out of the field you want, e.g. local!names1: property(local!array1, "name") *index() does the same thing*

local!names2: property(local!array2, "name")

Check to make sure those are arrays of what you want, e.g. {"bob","bill","mary"} and {"joe", "john", "mary")

Then another local variable which just stores the difference of only the field, local!nameDiff: difference(local!names1, local!names2)

Hopefully, by stripping the field out of the CDT and diffing it by itself, you can avoid confusing the difference function.  But then you have to index both of the CDT lists from your diff list to get all the associated data back, unless you were only going to use the diffed property.  If that was the only data you're going to use you're done, otherwise the last step is needed.

Yet another local variable, local!finalArray: union( index(local!array1, whereContains(local!nameDiff, local!array1.name), index(local!array2, whereContains(local!nameDiff, local!array2.name) )

*in short all the stuff from array 1 that matches union all the stuff from array 2 that matches

I was able to implement this approach and got it working as expected. Thanks David!