Limiter
Limiter is a dynamic signal processor used to attenuate peaks of stronger signals which exceed the specified input power (for example 0.3 dB). Unless used deliberately to create a distorted sound, the listener should typically not notice the usage of a limiter on the audio. The signal should keep its frequency response and only short unwanted peaks of the audio signal will be attenuated.
Hard "brickwall" limitation means the attenuation of the volume up to the point where it directly affects the shape of the waveform, not just the range of its amplitude. In this case, the peaks of the signal are attenuated in such a manner that it creates new (odd) harmonic content, noticeable distortion and a change to the sound's color.
Audio used for vinyl manufacturing should never contain hard "brickwall" limitations.