414/424
414 and 424 are sibblings. 414 is a very basic 4-tracker, it's good for throwing down ideas and it might be good to start out with if you haven't done any multitrack recording before. Anything the 414 does, the 424 does better. More inputs, better EQ (3-band against 2-band on the 414), 6 separate channel sliders (it can of course still only record on 4 channels) the 414 has 4. The LED-window on the 424 is much better than the simple channel LEDs on the 414. Tape transport buttons (play/rec/stop etc) are mechanical on the 414, you know like on the old boom boxes when you pushed play you acutually had to PUSH with some physical power. The 424 has electronic transport; you can push buttons with your nose if neccesary. i could go on and on. To sum it up 414 very basic. 424 is better but still basic. You'll grow out of both of them, very quickly and quickly respectively.
If it's down to these two machines and the difference in price is no problem, i'd go for the 424. No question there. But then again these are still analog cassette tape machines. A low budget hard disc MTR isn't that far off in price, but it's light years ahead in sound quality compared to any tape based portastudio.
Cheers and good luck with your recordings,
mm