You also claim that in slavery and genocide victims are rounded up en masse . This is often true, but with many exceptions. In biblical days people were often sold into slavery as individuals. Even during the Holocaust, though every attempt was made to round up people en masse , and most people were caught that way, logistics didn't allow that type of roundup to operate in every case. One has to clearly define genocide to decide what is unambiguously genocidal.
Many historians discern between ethnic cleansing and genocide largely on the basis of intent.
Other important differences are also attatched to the issue of intent. Torching villages, killing men, and even wiping out communities are often done without the intent to eliminate an entire people. Armenians in Turkey were safe if they lived in Smyrna or Constantinople or in some cases if they were willing to convert to Islam. Jews during the Holocaust were sought out by Germans wherever they could reach them, and conversion was not a viable option. Moreover, since the intent was genocide, and not ethnic cleansing, as many women of child-bearing age as possible were targeted, not just men and boys.