Is kares a greater punishment than capital punishment, or vice versa?

Question

In many cases (e.g., no warning, no witnesses) a capital crime is not punished by a beis din, but instead the offender gets kares. Let's assume for the purposes of this question that kares includes punishment in the afterlife (and is not only dying before one's time).

Now, from this answer it almost seems that punishment by the court is better than an afterlife punishment. There we have an offender whose crime is so heinous that he can't get a kapparah through beis din's execution. Presumably, though, he still gets punished in the afterlife. So we see that punishment in the afterlife is a greater punishment, and that that offender wasn't 'deserving' to get the lesser punishment on Earth. Thus here we have kares > capital punishment

But how can this be, if kares is usually given for less severe violations of the same sin? If someone is warned by two witnesses and still blatantly continues doing the sin, that sure seems like a more severe offense than if he did it in private, overcome by his passions. So we really ought to have capital punishment > kares.

Answer 1

Meseches Megillah (daf 22b) says that an Aliya, or a Torah reading, is added every time we add something. For example: from weekdays to Rosh Chodesh, we add mussaf, therefore Rosh Chodesh has 4 Aliya’s while weekdays only have 3. The Gemara then goes on to say: ביום הכיפורים דענוש כרת שישה, שבת דאיכא איסור סקילה שבעה.- on Yom Kippur there are six, because the punishment is kares, while on shabbos there are seven because the punishment is s’kila, one of the capital punishments. Therefore capital punishment is a worse punishment (it is “added on” to s’kila)

Edit: I just realized that in Megilla (daf 23a) there is a Tanna who argues and says that on Yom Kippur we read 7 aliyot, and on shabbos we read 6, presumably for the same reasons as above. In the end though, the Halacha is like the first Tanna

Answer 2

The Gemorrah discusses that explicitly (I'll let others to provide a standard answer). But spiritually, Karet is "higher" as it addresses higher parts of the Jewish soul.

I've answered that there #7: https://judaism.stackexchange.com/a/100212/15579

Let me explain how my answer is different and even opposed from the standard on (above):

Let me provide you with an analogy, a kid might see a wound that bleeds because it's local but he can't see his leukemia because it's so big for him. For him, the wound is far more severe than leukemia, because it is something he can perceive, he can't fear something he can't perceive.

However, we all know, that leukemia is far more dangerous and lethal than a simple wound and needs far more difficult treatment.

Similarly, the Earthy Beis Din has limited authorities, only to judge the sins that are "local" to Nefesh, that can be treated with simply killing the sinner after he atones. He continues straight to Eden or whatever and there's no "danger" to his afterlife.

But in case of a more serious sin that affects his Neshama or even higher parts, there's a danger of dying out completely (ונכרתה הנפש ההיא), to be cut out from Hashem completely. And that condition can be treated only by Hashem himself, that's why for us it seems less serious.

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For @Yaakovdean, this is similar to what AriZ"l writes about Tzizis that's מקיף and therefore לית ביה תפיסא. Hence it can be Halachicly "downgraded" to a mop when finished, unlike תשמישי קדודה that have perceivable Kedushah.