Start with the list of mortal sins for each and do a comparison.
You’ve inadvertently struck upon a core difference there.
The west would (and I assume does) have such a list; the east would not.
The west is quantitative and tends to want detail; the East is qualitative and is fine with mystery (and indeed tends to prefer it)/
The west has a more judicial approach to sin; the East has a more medical approach.
Which brings us full way around to . . . the East doe not distinguish between mortal and venial sin.
This does
notmean you won’t find plenty of writings by Eastern theologians about mortal sin. The West would be bothered by this; the East is not . . .

The East
does have about four sins that are handled separately due to their severity (murder, striking a priest, adultery, and some blasphemies).
In another coupe of posts, the usual suspects will probably appear and turn this thread into yet another one of their battlegrounds where they use selected quotes out of context to try to get one another to confess to all fault of the schism, and which “split” from the other

. But until then, information will flow . . .
And then some Westerners will get truly scandalized when they realize that the Sacrament of Anointing is performed for the
entire congregation on Wednesday of Holy Week after the pre-sanctified liturgy . . .
hawk