In November, Apple (AAPL 0.23%) began selling the iPhone X. The device represented a radical redesign of the popular smartphone, and was widely expected to trigger a significant upgrade cycle among its installed user base, and boost unit shipments significantly.

However, that expected large increase in iPhone unit shipments didn't happen during its peak sales quarter -- instead, Apple reported unit shipments fell 1% year-over-year. And it's clear from the company's financial guidance for the current quarter that iPhone X sales momentum evaporated surprisingly quickly.

Apple's iPhones in a "mosaic" pattern.

Image source: Apple.

The iPhone X failed to meet sales expectations even when it lacked significant competition, but with the launch of the Samsung (NASDAQOTH: SSNLF) Galaxy S9, it seems that Apple has been beaten at its own game. 

Here are two ways the Galaxy S9 outclasses the iPhone X. 

1. Better camera

In DxOMark's battery of camera tests, the iPhone X achieves a score of 101 in still photography quality, and an 89 in video quality. Its overall score is 97. 

The Galaxy S9 Plus edges out the iPhone X in both, notching a score of 104 for photography, and a 91 for video. Its overall score is 99. 

This isn't a huge victory for Samsung in absolute terms, but it's important to keep the following context in mind: Prices for the iPhone X start at $999 for the version with 64GB of storage, and jump to $1149 for the 256GB model, while the Galaxy S9 Plus -- a device with a bigger and better screen (more on that later) -- costs just $840. 

Considering how important camera quality is to smartphone buyers, Samsung's ability to provide better images for less money seems like a significant blow to the value proposition of the iPhone X.

2. Better display

According to a new report published by DisplayMate, which regularly rates the display performance of Samsung and Apple devices, the Samsung Galaxy S9 has a superior display in several key ways to that of the iPhone X. 

First, it has superior color accuracy. It also suffers from a less dramatic color shift when viewed off-axis. And given its substantially higher pixel density -- 570 pixels per inch compared to just 458 pixels per inch on the iPhone X -- the display on the Galaxy S9 is, of course, sharper. 

The main advantage that the iPhone X seems to have on this front is that its display can achieve significantly higher brightness if one uses the manual brightness settings (though the display on the Galaxy S9 can achieve higher brightness when the phones are adjusting their levels automatically). 

Although it might seem as though Apple at least narrowed the competitive gap with Samsung on this front with the iPhone X, it is, in fact, the other way around. The iPhone 7 had a substantially more color-accurate display than the Galaxy S8, but the iPhone X falls behind the Galaxy S9 on color accuracy. 

This is a disappointing result from Apple, especially considering that the Galaxy S9 has a similar-sized display to the one on the iPhone X, but a price tag that's $300 smaller. 

Foolish takeaway

There is nothing wrong with Apple selling smartphones that start at $999 and go up from there -- higher-priced phones can incorporate more innovation and better technology than lower-priced ones. 

The problem here is that if Apple wants to sell a device at a premium price, it had better be sure to offer technological leadership in the areas that matter most to buyers. The display and the camera are arguably the two most important differentiating features among smartphones, so those are areas where Apple must deliver a far-and-away better user experience than the competition if it wants to continue to command premium prices.