A difference in divisions
Deuteronomy 28 completes a major section in the Pentateuch wherein Moses has finished his rehearsal of the Sinai Covenant before beginning a new section in chapter 29 on a "new covenant" for the future. The received Hebrew Masoretic Text (MT) included 29:1 as the 69th verse in chapter 28. Thus chapter 28 ends in the MT at 28:69 while the English makes 28:69 the first verse of chapter 29. The difference is significant because it effects how we read 29:1 [28:69 MT]. The verse in question reads, "These are the words of the covenant which the LORD commanded Moses to make with the people of Israel in the land of Moab in addition to the covenant which he made with them at Horeb."
What's the difference?
The way the MT divides the verse makes it difficult to see chapter 29 as introducing Moses' vision for a future "new covenant" which is different from Sinai/Horeb. Rather, it makes 29:1 seem to refer backwards to all that we just read in Deuteronomy. This means that Deuteronomy 1-28 is the other covenant that the LORD made with the people in addition to Sinai. However, if the verse is meant to introduce what follows in 29-34, then 29-34 are about a future covenant subsequent and distict from Sinai. John Sailhamer notes that this seems to be how the NT authors understood these last chapters since they see in them "a prophetic message regarding faith and the coming of Christ (e.g., Ro 10:6-13)" (The Pentateuch as Narrative pg. 472).
How can we tell where to divide it?
Figuring out just where the "these" in "These are the words.." points (backward to what precedes, or forward to what follows) is a function of careful text linguistic analysis of the Hebrew Bible and how such a phrase is typically used therein. It seems pretty clear that in at least two very clear spots in the Pentateuch (Ex 1:1 and Deut 1:1) the same phrase points forward to what follows in the text as a kind of title, announcing what follows. Although a comprehensive analysis of this syntax would help determine the issue more definitively, these other verses in the Pentateuch suggest that the same meaning is intended here in Deut 29:1 [28:69 MT]. Therefore, I think the English chapter division is likely more consistent with the author's intention, and it helps guide the reader into a more future oriented "new covenant" reading of the last chapters of Deuteronomy.
The real difference
The issue effects how one understands the very message of the Pentateuch, i.e. which covenant the author wants promoted. The question is whether the author's message is that the reader should look back and do a better job at keeping Sinai, or look forward to a new covenant work of God and the coming of The Messiah. That's pretty big stuff.
