list previousItems = [
                        "Name1","Name2","Name3"
                    ];

list currentItems =  [
                        "Name1","Name3","Name4", "Name5"
                    ];
default
{

    touch_start(integer total_number)
    {
        list addedItems;
        list removedItems;

        integer index;
        for (; index < llGetListLength(currentItems); ++index){
            if (!~llListFindList(previousItems, (list)llList2String(currentItems, index))){
                addedItems += llList2String(currentItems, index);
            }
        }
        llOwnerSay("Items added: " + llDumpList2String(addedItems, ","));

        index = 0;
        for (; index < llGetListLength(previousItems); ++index){
            if (!~llListFindList(currentItems, (list)llList2String(previousItems, index))){
                removedItems += llList2String(previousItems, index);
            }
        }

        llOwnerSay("Items removed: " + llDumpList2String(removedItems, ","));

    }
}