When two boats share the same hull type — in this case both the Weld-Craft RL 44 (15 ft.) 2007 and the Weld-Craft RS 70 (18 ft.) 2010 are flat designs with aluminum construction — the buying decision usually comes down to a handful of practical questions: how many people are you putting on the water, how far do you trailer, and what does your tow vehicle weigh?
Both boats share a closely matched power ceiling — 25 hp for the Weld-Craft RL 44 (15 ft.) 2007 and 40 hp for the Weld-Craft RS 70 (18 ft.) 2010. Real-world performance will come down more to which motor is actually bolted on, its load at the time, and whether it's a 4-stroke or 2-stroke setup.
For family outings this is probably the sharpest distinction between the two. The Weld-Craft RS 70 (18 ft.) 2010 is rated for 5 passengers, while the Weld-Craft RL 44 (15 ft.) 2007 caps at 4. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Weld-Craft RS 70 (18 ft.) 2010 could be the deciding factor.
Bottom line: Choose the Weld-Craft RS 70 (18 ft.) 2010 if your priority is putting more people on the water — it handles 5 passengers and at 18,0 ft it has the deck room to back that rating up comfortably. The Weld-Craft RL 44 (15 ft.) 2007 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 4 that costs less to run day-to-day.