do not trust such a person's pretty speeches, since in the heart lurk seven abominations.
There are six things that Yahweh hates, seven that he abhors: a haughty look, a lying tongue, hands that shed innocent blood, a heart that weaves wicked plots, feet that hurry to do evil, a false witness who lies with every breath, and one who sows dissension among brothers.
Despite the commonality of "seven", "heart" and possibly "abomination" and the fact that both passages appear in Proverbs I would say that they are not the same.
I would compare the two passages as two pies (like in a pie graph) and each pie is cut into seven pieces. The first pie pieces are:
The sowing of discord being seventh might be being emphasized.
The second pie is also cut in 7 pieces but they are not identified.
So if you drew a line from the first pie from "heart that weaves wicked plots" over to the second pie the then seven pieces are seven evil plots. We might see in it perhaps an allusion to the plot of Haman and the plot of Joseph's brothers against him, etc. But they are not explicit in the passage.
It may be relevant that in Matthew's/Jesus' list of evils proceeding from the heart he lists seven:
Mat 15:17-20 KJV - 17 Do not ye yet understand, that whatsoever entereth in at the mouth goeth into the belly, and is cast out into the draught? 18 But those things which proceed out of the mouth come forth from the heart; and they defile the man. 19 For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies: 20 These are the things which defile a man: but to eat with unwashen hands defileth not a man.
See also Catholicism's list of Seven Deadly Sins:
pride, greed, wrath, envy, lust, gluttony and sloth.
A froward / proud heart Prov. 11:20 & 16:5 (froward being the opposite of upright.) ‘abomination’ in A.V.
False balances Prov. 11:1 (= 'tricky' business dealings). ‘abomination’ in A.V.
Lying lips Prov. 12:22 (liars will not inherit the Kingdom of God, Rev. 21:8). ‘abomination’ in A.V.
Thoughts of the wicked Prov. 15:26 ‘abomination’ in A.V.
The ways of the wicked Prov. 15:9 ‘abomination’ in A.V.
Whoever justifies the wicked and condemns the just Prov.17:15. ‘abomination’ in A.V.
Hatred shown in lies and deceit and tale-bearing Prov. 26:24-26 One of the 7 abominations in his heart in A.V.
Of course, the Bible has a lot more to say about things that are an abomination to God than that. Of note is that his idea of abominations rarely squares with human views. Jesus made that point when he said that what God calls abominable, men delight in:
"Ye are they which justify yourselves before men; but God knoweth your hearts: for that which is highly esteemed among men is abomination in the sight of God." Luke 16:15
See, for example, how many billions of people today totally disregard God's warning about this particular abomination, graven images, idols of gods:
"Neither shalt thou bring an abomination into thine house, lest thou be a cursed thing like it; but thou shalt utterly detest it, and thou shalt utterly abhor it; for it is a cursed thing." Deuteronomy 7:25-26
Your second question asks if the two sets of seven abominations in Proverbs are the same 'thing'. The wording can vary, but the common denominator in both is corruption in the heart. God reads the hearts and knows the minds of all, and has warned us that our hearts are deceitful, treacherous, and that we cannot know them. That is why God's view of abominations seem so strange to so many people. They are used to a way of life that not only encourages pride, vanity, lying, trickery, gossip and hatred, but without them, you are going to find the herd trampling all over you in their rush to be acclaimed in this sinful world.
"Seven" should simply be a metonymy for "many" or many times; sevenfold, rather than a reference to a list. Ellicott commentary says:
Seven abominations.—See above on Pro. 26:16, and comp. “seven spirits” (Mat. 12:45) and “seven devils” (Mar. 16:9).
On Prov 26:16 The sluggard is wiser in his own eyes than seven men who can answer sensibly., he mentions: Seven men.—A round number. (Comp. Pro. 26:25; Pro. 6:31; Pro. 24:16.)
Proverbs 26:25 (ESV) when he speaks graciously, believe him not, for there are seven abominations in his heart;
Proverbs 6:31 (ESV) but if he is caught, he will pay sevenfold; he will give all the goods of his house.
Proverbs 24:16 (ESV) for the righteous falls seven times and rises again, but the wicked stumble in times of calamity.
John Gill mentions that Ibn Ezra, an 11th century Rabbi related it to the 7 abominations.
for [there are] seven abominations in his heart; a multitude of wicked purposes, schemes, and designs, which he has formed there against you, and which he only waits a proper time to put in execution; things abominable to God and men. Aben Ezra thinks reference is had to the seven abominations in Pr 6:16.
