The X series laptops are designed to be thinner and more portable, while the M series prioritizes performance. However, there are a few other factors to consider:

1. Graphics Card: The M series can be configured with higher-wattage GPUs compared to the X series, which translates to better gaming performance.

2. Thermals: Due to their slimmer design, the X series laptops may run a bit hotter under heavy load compared to the M series. However, both lineups have excellent cooling systems, and I haven't experienced any thermal throttling on either my M15 R4 or X17.

3. Display: Both series offer high-refresh-rate displays, but the M series can be configured with a QHD 240Hz panel, which is a sweet spot for gaming and content creation. The X series maxes out at a FHD 360Hz or a 4K 120Hz panel.

In terms of build quality, both the M and X series are top-notch. They feature sturdy aluminum chassis, premium materials, and a sleek design. Alienware laptops are known for their exceptional build quality, and you won't be disappointed with either series.

For gaming and content creation, I would lean towards the M series due to the higher-wattage GPU options and the availability of a QHD 240Hz display. However, if portability is a top priority for you, the X series is still a great choice and can handle demanding games and creative workloads with ease.

Regarding value for money, Alienware laptops are premium machines and come with a higher price tag compared to some other brands. However, you do get what you pay for in terms of performance, build quality, and features.

Ultimately, the choice between the M and X series comes down to your specific needs and preferences. If you prioritize performance and don't mind a slightly thicker chassis, go for the M series. If you value portability and don't need the absolute highest-end specs, the X series is a great option.

X series is more compact, and M series is more powerful.