Of course, if we define "slavery" as "harsh, senseless, cruel, violent, selfish abuse of other humans", then (I hope in the vast majority of cases), no, contemporary employment and slavery are different in kind.
But I do think there are reasons to doubt this second definition to have been systematically accurate.
For example, it makes no sense, from a cost-effectiveness point of view, for a slave owner to mistreat his slaves that much: it's in his best interest to make sure they live decently. Or, in a society where slavery is culturally acceptable, hence widespread, many slave owners must not have been this inhumane.
I'm not saying it never occurred, merely that there are good reasons to think that it wasn't as systematic as we tend to believe.
What's the cost-effectiveness of a master selling one of his female slave's children away from her, which was a regular occurrence?
Accurately answering your question requires writing a thesis: one needs extensive access to accurate data spanning thousands of years, a solid grasp of history, psychology, ancient customs, etc. Those situations are full of subtle nuances; what historians currently understand might not even be that accurate.
OTOH, casting reasonable doubts by assuming a fair amount of people weren't too stupid is less bold of a position than "slave owners were living devil", but at least it's honest.
(Which doesn't imply that "slave owners were living devil" isn't true, merely that it's dishonest to say that it's true, because it's too difficult to know for sure).
Slavery is an old thing[0]. Even assuming the death rates are correct, one can't honestly conclude that what happened in the West in the past 500 years is similar to what happened, say, in Antiquity in the West[1] - and that's what most relevant to Aristotle - or amongst ancient Jews[2].
I know that there are too many unknowns for me to even have a clear thesis to begin with.
[0]: https://en.wikipedia.org/wiki/Slavery#History
You seem curiously attached to the happiness in slavery fantasy.
It's not because I don't share your viewpoint that I share its exact opposite either.
Even in the case of the house servant you imagine the typical slave to be, you have not considered factors like having their children sold away from them, or the death of a kind master leading to being sold or inherited by a wicked one.
There are no happy slaves.
Note that I'm assuming an objective/neutral definition of "slavery", and not the usual "slavery=bad thing".
Now, we could argue that it's a matter of education, circumstances, etc. But surely you must have met people who would obstinately refuse to listen to reason, entertaining their own misery. At least IME, it's sadly a common trait.