Ramban: Because a. whereas there the Torah discusses an animal that strays from the path ("To'eh ba'Derech") - where one merely needs to return it to the path, here it adds that if it has wandered far from the path ("Nidachim"), one must return it, and b. Whereas there the Torah refers to an ox or a donkey that is lost, here it adds a lamb, which is considered totally lost. ¹

Bava Metzi'a, 33a: The Chachamim therefore explained Re'iyah which includes Pegiyah - a distance of one Ris (a seven and a halfth of a Mil = a hundred and sixty-seven and two-thirds Amos).

Oznayim la'Torah: After teaching us in Mishpatim, the Mitzvah of overcoming one's Yeitzer ha'Ra and returning the lost article of one's enemy, the Torah refers here to the ox of one's brother to teach us returning a lost article, is a Mitzvah in and of itself and that the Torahmentions "Shor Oyivcha" in Mishpatim to give precedence to the ox of one's enemy over that of one's friend.

Bava Metzi'a, 27a: It mentions "Shor" to include the shearings on its tail and "Seh" to include its wool ¹ in the Don of Hasavas Aveidah.

Sifri: It implies that one is only Chayav to return the animal if its it is obviously lost - a cow runing in the vine-yard among the vines, ¹ but not if one finds it grazing by the roadside.

Rashi #1: It implies that one may not hide one's eyes from a lost article - to pretend that one did not see it.

Rashi #2 (citing the Sifri): It implies that sometimes one may or must ignore it. ¹

Bava Metzi'a, 30a: The Torah writes "Vehis'alamta meihem" (positive), implying that one is sometimes permitted to hide one's eyes from alost article - 1. where he is a Kohen and it is in a Beis-ha'Kevaros; 2. where he is an elder and it would be below his dignity to return it and 3. where his loss of work exceeds the value of the article.

Bava Metzi'a, 30b: "Hashev" implies even a hundred times, ¹ and the Torah adds "Teshivem", since that is the way people speak.

Bava Metzi'a, 31a: To teach us that one may return the article to the owner's garden or his wood-storage area ² - to teach us that one may return the lost article to the owner without his knowledge. ³

Sifri: To tech us that he must return the lost article into the owner's domain - to a location where the owner will see it and look after it. ¹ Otherwise, he will be liable if it gets lost again,