When you hook up a tape recorder to your preamp, you need a connection from the output of the preamp to the input of the recorder, and you need another connection from the output of the recorder to an input on your preamp.
The output from your preamp to the recorder usually needs to be a line level signal that is not affected by your preamp's volume setting or tone controls. Of course, your preamp's source selector determines the signal that is transmitted (CD, LP, Tuner, etc, but not tape, which could cause a dangerous feedback loop).
Often, users want to hear if the recorder's tape is capturing the signal properly, so their preamps have a "tape monitor" button. This button can cause the preamp to connect the signal transmitted FROM the recorder to the preamp's volume and tone controls, then pass it on to the amp to be played back. This happens even though the preamp's selector switch is still set to another source (say, CD), and the other source is what is being sent to the recorder for recording.
Accordingly, you can see that the tape loop allows you to select one source to send out the preamp's tape out sockets, while choosing to play back and listen to another source (i.e., the recorder itself) through your amp and speakers.
This gets interesting if you have things like equalizers or other signal modifiers. You could use your preamp's source selector switch to pick a source (say, LP), let the preamp send this signal out to the equalizer (hooked up in place of the tape recorder), have the equalizer modify the signal, then have the equalizer send the signal back to the preamp, and play the modified signal to your amp and speakers by pushing the tape monitor button.
To your question, the tape outs are likely not the same as pre-outs because the tape outs would not be affected by your preamp's volume control, tone controls, or any other similar on-board signal modification/control devices. For example, it would probably be unacceptably loud and you wouldn't have any control over the volume.
Hope I haven't been too confusing.