From the linked article:
Despite attempts at modernization, Liaoning's and Shandong's capabilities are limited by their employment of the short take-off, barrier-arrested recovery (STOBAR) system, which utilizes a ski-jump ramp at the bow to get jets airborne under their own power.
This imposes limits on the weight of the jets at take-off, as they need to be light enough to lift off the deck under their own engines. Consequently, force multipliers like airborne early warning aircraft and dedicated aerial refueling aircraft cannot operate from Liaoning and Shandong.
The air wings of the Liaoning and Shandong, which consist of 24 to 32 jets and 12 to 17 helicopters, respectively, are less than optimal for this setup, as the backbone of the wings, the J-15 fighter, is the heaviest carrier-borne aircraft in service. This means it has to carry a limited armament and fuel load, reducing its capabilities and combat range.
Liaoning is a part-rebuild, part-completion of a Soviet design whose construction was interrupted by the collapse of the USSR, and Shandong is a Chinese-built semi-clone thereof. IIRC, the Soviet Admiral Kuznetsov was renowned for having to be accompanied by an ocean-going tug. Whether this problem is relevant to Liaoning,

. The bigpoint about the design is that its catapult-less ski-jump take-of design limits the aircraft that can be deployed now and in the future. China's home-brew jet engine manufacturer is having trouble getting high thrust from its designs, so that will also impact what can currently be deployed and into the near future. Chinese airwing, 32 jets and 17 helicopters (assuming the maximum of both can be carried); Nimitz class typical airwing, 24-36 Super Hornet strike fighters, 20-24 F-18C fighters, 4-6 EA-18 Growlers, 4-6 E2C or D Hawkeyes (AEW), and 6-8 helicopters; Nimitz class maximum airwing is 85 aircraft of mixed types.
Fujian appears to be that more advanced and capable design.
Measuring 1,036 feet long and displacing over 80,000 tons, Fujian is larger than its predecessors. The most obvious advantage of its larger size is that it enables a larger airwing, which is believed to number approximately 60 aircraft.
The most important upgrade on Fujian, though, is its employment of a catapult-assisted take-off barrier arrested recovery (CATOBAR) system, which uses a catapult to launch an aircraft off a carrier's deck. While the CATOBAR system isn't new, Fujian is one of only two carriers in the world equipped with electromagnetic catapults (EMALS), the other being the new USS Gerald R. Ford.
An EMALS catapult enables Fujian to launch heavier aircraft than steam catapults, which means a more diverse air wing. China is currently developing a host of new carrier aircraft, ...
Fujian has an actual catapult, which increases the range of aircraft that might be deployed. Given the USN's trouble making the electromagnetic catapult system work fully and China not currently being renowned for innovation, I think its current status uncertain at best. A 60-aircraft airwing is larger, but this maximum is almost as many aircraft as a current typical (not maximum) Nimitz class airwing.
Not mentioned in the article (that I noticed) is that China's aircraft carriers are conventionally fueled. This limits their range and tethers them to land-based fuel sources and/or tankers (which are typically slower.
Realistically, China's aircraft carriers are very well suited for coastal defense and are suitable for regional power projection. But out into the open Pacific or Indian Oceans, their fuel tether and limitations (= outside of land-based air support) make them less than suitable.