import org.suecarter.tablediff._
def listsDiffString(leftList: Iterable[Product], rightList: Iterable[Product]): String = {
  def listReport(list: Iterable[Product]) =
    ReportContent(
      columnHeaders = Seq(list.headOption.getOrElse(Nil).productElementNames.toSeq), // Scala 2.13+ for this
      mainData = list.map(x => x.productIterator.toSeq).toSeq,
    )
  StringTableDiff.diffReportToString(
    TableDiff.produceReportDiff(listReport(leftList), listReport(rightList)),
  )
}

case class A(b: Int, c: String)
listsDiffString(Seq(A(1,"x"), A(2,"y"), A(4, "c")), Seq(A(1,"x"), A(2,"z"), A(3, "c"))) 

+---------------------+
|b         |c         |
+---------------------+
|1         |x         |
|2         |[-y-]{+z+}|
|[-4-]{+3+}|c         |
+---------------------+

Compare left table
+----+--------------+
|    |col1|col2|col3|
+----+--------------+
|row1|m1,1|m2,1|m3,1|
|row2|m1,2|m2,2|m3,2|
+----+--------------+

to right table
+----+---------------------+
|    |col1|col2|col2.5|col3|
+----+---------------------+
|row1|m1,x|m2,1|m2.5,1|m3,1|
|row2|m1,2|m2,2|m2.5,2|m3,2|
+----+---------------------+

Produces these diffs, showing us that the cell in row1,col1 has
changed from m1,1 to m1,x and a whole new column (col2.5) has 
been added.
+----+----------------------------------+
|    |col1         |col2|{+col2.5+}|col3|
+----+----------------------------------+
|row1|m1,[-1-]{+x+}|m2,1|{+m2.5,1+}|m3,1|
|row2|m1,2         |m2,2|{+m2.5,2+}|m3,2|
+----+----------------------------------+