Mr. Fantasy, there is no such thing as an "SKM 140 microphone." An SKM 140 is a stereo set of two Neumann KM 140 microphones plus some accessories. A stereo set of two KM 184 microphones is also available. The main differences are that the KM 140 is a "modular" microphone while the KM 184 is not, and that the KM 140 is substantially more expensive than the KM 184; for stereo pairs it is even more so.
The KM 140 is made up of an amplifier and a capsule, both of which are part of a larger series of interchangeable components. If you have a pair of KM 140 you can attach other capsules of the series in place of the AK 40 cardioid capsules, and then you've got a pair of microphones with some other directional pattern and/or frequency response characteristic. Or you can substitute a pair of KM 100F amplifiers (bodies) in place of the stock KM 100s and you'll have a pair of microphones with a built-in low-frequency rolloff and the option for a steeper and higher rolloff which is very useful for dialog recording and public address applications. In addition there are special accessories such as cables and goosenecks which can go between the capsule and amplifier of the modular microphones to facilitate certain kinds of setups. But none of these options exist for the KM 180-series microphones.
Apart from that, the "acoustical design" (i.e. the capsule and the way it is exposed to the sound field) are absolutely identical between the KM 140 and the KM 184, and that is what mainly determines the sound quality. There is a minor difference in the electronics, with the KM 184 having slightly lower inherent noise (and requiring slightly greater current from the 48 Volt phantom power supply). But for recording live concerts that difference in noise level will never be an issue, since even at the quietest of moments the noise of any public venue will swamp the noise of either type of microphone by a considerable amount.
--best regards
P.S.: Your two photos definitely do not show the same two microphones. The upper photo is an M/S arrangement with an AK 20 figure-8 capsule on top (i.e. definitely not a cardioid) and some other capsule beneath it. The head-to-head pair of microphones, who cares what pattern or model they are--no one should ever set up microphones for stereo recording that way if there is any reasonable alternative available (and if there isn't, then create one!).