There are many factors that alter the frequency response of a recording, but while a decent digital recording system is quite flat from 20 Hz to 22 kHz (or more), many analogue systems exhibit a gentle rolling-off in higher frequencies through their usable range, and a more extreme drop-off at the high end.
Again, this varies with speed. Whether you use tape or vinyl, the recording and playback speed alters this significantly. Broadly speaking, higher speed equates to better high-frequency extension. (Interestingly, the speed of the needle relative to the groove on a 12-inch record is less than half its maximum by the time you get to the centre. This is why many mastering engineers avoid cutting grooves too close to the label.)
We can see (and hear) the effects by looking at this comparison of frequency response between the original digital recording and the cassette version of this cowbell sound:
The cassette version (in purple) is clearly more muffled in the high frequencies than the original digital recording (in orange).
Things improve in the top end when recording to a professional tape machine. In this case we’re dealing with the Studer A80. This is a classic professional reel-to-reel machine. The result is noticeably different to the cassette:
However, if we create a graph showing the difference between the digital and A80 versions you can see that there’s more than just a slight EQ roll-off going on:
We can see a similar effect if we compare the difference between a digital recording of a snare hit and a version of the same sound cut to vinyl: