NKJV - 15 I will meditate on Your precepts, And contemplate Your ways.
Psalm 119 is famously known for being acrostic poetry. Broadly defined, an acrostic is a composition, usually in verse, in which the initial letters of the lines (or last or middle letters or some such arrangement), taken in order, spell a word or phrase or follow the regular order of the alphabet. This last kind may be further described as an abecedarian, or alphabetic, acrostic. Psalm 119 is an alphabetic acrostic. The entire chapter of Psalm 119 is given over to acknowledging the wonderful gift of God’s Word to his people Isra'el. The psalmist uses poetry, synonyms, metonyms, and Hebrew acrostics to demonstrate the magnitude of the richness of having, knowing, and embracing God’s precious Word. To be sure, most English bibles recognize the eight verse acrostic formed by using the letters of the Hebrew alphabet to start each new line, and continuing for eight verses before moving to the next letter of the Hebrew alphabet (Aleph, Bet, Gimmel, Dalet, Heh, Vav, Zayin, etc). Within this rich genre of literature, the psalmist regularly employs poetic parallelism, where one word of one verse parallels another word in another line in meaning or in concept. In Psalm 119, the writer uses a variety of Hebrew words all intended to convey his love and appreciate for one single concept: the Word of God. For instance, in the verse in question (Ps. 119:15), “precepts” is parallel to “ways”: “I will meditate on your precepts and fix my eyes on your ways.” In Hebrew this verse is only four words! I will transliterate it from the original Hebrew for you: “B’pikudecha asichah v’avitah orchotecha.” The original Hebrew word for “precept” in this verse is “pikudei.” The original Hebrew word for “ways” in this verse is “orach.” So to reinforce our understanding of this verse—and indeed this entire Psalm 119—to the psalmist, he does not want his readers to focus on any surface-level or functional differences between the differing Hebrew terms he uses to describe the Word of God. Indeed he uses a variety of differing terms. His poetry is simply meant to inspire awe and wonder at the magnitude and majesty of the incredible Word of our God. So, to answer your question succinctly, "precepts" and "paths" really are two different Hebrew terms, but in this psalm, they are meant to be experienced by the reader as complimenting one another, with the purpose of describing the exact same thing: God's Word.