JST Matt 7

Why teach ye men the law and the commandments, when ye yourselves are the children of corruption? 

For the world cannot receive that which ye yourselves, are not able to bear; wherefore ye shall not give your pearls unto them.

JST Matt 21

And when the Lord therefore of the vineyard cometh, he will destroy those miserable, wicked men, and will let again his vineyard unto other husbandmen, even in the last days, who shall render him the fruits in their seasons. And then understood they the parable which he spake unto them, that the Gentiles should be destroyed also, when the Lord should descend out of heaven to reign in his vineyard, which is the earth and the inhabitants thereof. When the marriage was ready, he and my dinner is ready, the servants hat his servants were dead, wherefore all do not have on the wedding garment.

Other differences in JST Matt 24:

Reference to the “elect”:

vs 27 – “so likewise shall mine elect be gathered from the four quarters of the earth”

Reference to the “desolation of abomination, spoken of by Daniel the Prophet”:

vs 32 – “And again shall the abomination of desolation, spoken of by Daniel the prophet, be fulfilled”

vs 36 – “then shall appear the sign of the Son of Man in heaven, and then shall all the tribes of the earth mourn”

vs 37 – “And whoso treasureth up my word, shall not be deceived, for the Son of Man shall come,.. and they shall gather together the remainder of his elect from the four winds”

See:

http://www.boap.org/LDS/LDS-scriptures/Pearl_of_GP/Matt24.html