In general, both products are similar, but I would prefer the DeWalt cordless drill because it seems to be more powerful even though they have the same voltage (18 V-20 V). The DeWalt drill also has a longer battery life and the design is lighter and easier to carry and use. Milwaukee offers a wide selection of tools that will all work on the M18 platform. In fact, there are more than 150 tools in the range.
But DeWalt beats it with a wide selection of more than 200 tools that run on its 20 V batteries at most. And if you were to also count all the tools in the FLEXVOLT range, that number would be much higher. Milwaukee and DeWalt are fairly evenly matched in the battery department. Both companies use lithium-ion batteries that can last more than an hour on a single charge.
Dewalt is the largest company compared to the Milwaukee tool company, with 13,000 employees not counting the more than 60,000 employees of Stanley Black & Decker. Even for tools where DeWalt had a clear performance advantage over the more similar model available in Milwaukee, the DeWalt tool had a much lower price. There will always be an imbecile who chose yellow, thinking it was the same as red, and tried to power big tools with small batteries, or red instead of yellow, trying to make big tools work with batteries that weren't Flexvolt, because they would work well if they were from the Red brand.
Milwaukee toolsare a great option, but they can't match the affordable prices and incredible value of DeWalt.
However, I should add that Milwaukee was the first company to include lithium-ion batteries in its power tools. All Milwaukee M18 tools and batteries are compatible, but with practical limitations, since not much can be done when you combine a compact battery with your heaviest tools. There's no denying that both Milwaukee and DeWalt offer compact power tools, but I think Milwaukee once again has the advantage in this regard. Both Milwaukee and DeWalt started in the 1920s and have since established themselves as leaders in the power tool industry.
At the end of the day, if the most important thing to you is to stay on a battery platform and know that all your tools will work with all your batteries, Milwaukee is the way to go. Stanley Black & Decker is the tool giant that owns Dewalt and also owns other brands of power tools, such as Porter-Cable, Craftsman and Lenox. Many of the Makita 2x tools I've seen have a reasonable space between the currently available batteries when placed in the tool. When it comes to the power tool industry, there are two brands that stand out above the rest, and they are DeWalt and Milwaukee.
Dewalt portable tools also come with a lifetime warranty, and some pneumatic tools come with a whopping 7-year warranty, plus 1 year of free service and a 72-hour money-back guarantee.