Some-thing strange about MP3 Players/Recorders !!!

Hi,

Can some-one be kind enough to answer my questions which are in bold text ?

What is "Organic EL screen" ?

I am new to MP3 players.
I want to buy one that does not only play mp3 files but also play and record the radio aswell as record voice/sound/dictation.

Sometimes I come across great ones but they don't have any rechargeable batteries and the ones that do have them have rubbish functions.
And so, if I buy the one with great functions and no recharge-able batteries then if I replace them with recharge-able batteries then will my MP3 Player-Recorder work with-out getting screwed-up ?

Anyway, I am not interested in the "flash memory" ones because even though they are "remove-able memory" they do not contain that much space. And, those that do are too expensive. I am not going to buy IPOD because they are only suitable for MACs (I think).
And so, I thought it would be best if I get the one that has "internal memory" (hard drive) that can hold music aswell as data files so I can easily transfer important data files from my pc to it and carry it on my pocket always.
As I was shopping around, I came across :

MP3 USB Key, Internal Memory and Hard Drive (3 types of MP3 Players/Recorders).
Now, I am spoilt for choice.
I mean, what's the difference between the "Internal Memory" type and the "Hard drive" and the "MP3 USB Key" type MP3 Players/Recorders ?
I mean, the "Internal Memory" type and the "Hard drive" MP3 Players/Recorders are the same thing ain't it ? Because the "Hard Drive" MP3 Player/Recorder also has "Internal Memory". Don't understand this mystery. Am really getting puzzled.
If you say that the "Internal Memory" type and the "Hard drive" MP3 Players/Recorders are the same thing then why has this website categorised them differently ?
Check the links on the left-side of the webpage :

http://www.pixmania.co.uk/uk/uk/sound/4/onglet.html

Check under the section "MP3 PLAYER (220)" and you will see that there is one section "MP3 Hard drive" and another section "MP3 with Internal Memory".
I am going to ask the website these questions but as you know usually websites take a week to reply and I need answers quick and so I need your excellant help !

Please note that I am not spamming the links because I don't own them and I am not affiliated with them either otherwise I would have listed my referral links.

Also, if the "MP3 USB Key" type is a "remove-able memory" then why do the descriptions of each MP3 Player/Recorder on the following link advertise some "MP3 USB Key" Mp3 Players/Recorders that they do not have "removeable memory" ?

http://www.pixmania.co.uk/uk/uk/79/xx/xx/15/4/criteresn.html

Strange !

Oh by the way, the ones that have "dictaphone", would they be able to record secretly conversations which I have with others ? I mean, from how far can they record voice/sound ?

I have some more questions regarding the technical words about MP3 Players/recorders and I have posted them on the thread "What is all this about MP3 USB KEY ?".
Please try to answer them.
Kindly help this fellow find the right MP3 Player/Recorder for himself.

Cheers.