There are actually quite a few difference between these similar "sounding" tablets that had ought to consider when making this decision:
SOC: Both the Galaxy Note 2014 Edition (N14) and the Nexus 10 (N10) are using an Exynos chipset. That said, the N10 uses an older quad-core 1.70GHz Samsung Exynos 5250, where as the N14 uses a newer Exynos 5420 at 1.9Ghz. The later is an octa-core (theoretically, as far as I know, it's not implemented as such yet through drivers) while the 5250 is a straight quad core.
Memory: GN14 3gb of Ram, Nexus 10 2gb.
Having owned both - you're going to have an easier time multitasking with the 3gb of ram. That's not to say performance is wildly different - but between the two features above, there is a noticeable difference.
Both feature a 2500*1600 panel, but the panel on the N14 is FAR superior to the panel found on the N10 - it's night and day. The color calibration is there, it's not washed out - unlike most Samsung devices, it's not even oversatured. The addition of the Wacom digitizer should be mentioned as well (it's what makes the note the note

) - giving you access to real actual handwriting ability - where it just doesn't exist on the N10.
Software: Another night and day category. It's preference, but the N10 runs stock Android on Android 4.4, while the N14 runs (at present) 4.3 with a heavily modified version of Touchwiz over top. Some people love Touchwiz, some hate it - for me...I'm annoyed with its performance - but you do get a lot more customizability out of the thing...that's for sure.
Performance wise, I can share with you that the Nexus 10 is no slouch, but for gaming (for example) it's another night and day category. The N14 with it's newer SOC and GPU are just in a different class. The N10 has always (sadly) been Google's red headed step child. There's never been a good concerted effort to make the N10 appear like a flagship product - no accessories, the software optimizations just suck ask people who own one how well even the Google Now launcher runs on the thing (which isn't included in it's 4.4 update) - where things like transparent menu's are omitted.
Form Factor/Accessories: This is a give and take category.
N10:
The Good: I really liked the form factor of the N10: Rubberized back plate, rounded edges, front facing speakers, etc - all good.
The Bad: The damn thing was heavy, and I mean heavy by a 10' tablet standard. Comes in 603 grams and weight is wierdly distributed as a result of those awesome front facing speakers. Wasn't fun to use in portrait mode, and when holding in landscape, my hands were always covering the speakers.
The Ugly: The only officially supported accessory was the N10 "case," which is quite possibly the worst designed accessory of all time. It requires you to pop off the back panel and replace it like a hing, the front flap is basically a gel-filled neoprene flap that doesn't function as a stand...and the thing was ludicriously expensive.
N14:
The Good: Made by Samsung as a Samsung product, meaning there's a lot more in the way of official accessories. More on that in a sec. Form factor of the tablet is nicer - think a great big Galaxy Note 3 with buttons on the side versus the bottom. It's considerably lighter (which is a feat considering it packs in a lot more tech) at just 547 grams.
The bad: Made by Samsung as a Samsung product. It's made of plastic through and through, and that means physical buttons. Love them or hate them...they're there - one big physy - and two capacitive buttons indicating you're supposed to hold this thing in landscape - I'm not a landscape guy - this annoys the **** out of me. Speaker placement isn't great and certainly the sound suffers as a result - though the tablet is much easier to hold on to in portrait.
The Ugly - That plastic back has the faux-leather stitching thing - take my advice...get a case.
Peformance and go-forward viability:
Here's the big nail in the coffin for the Nexus 10, it's nearly at end of life - the last couple of Android updates have been exceedingly slow getting to the device, and it's not the same software implementation on the N10 versus the N7. Take that for what you will. The N10 was never silky smooth in terms of performance, there I said it. The Exynos 5250 was a monster SOC - but it just wasn't monster enough to run the tablet with the insane panel that was on it (2500*1600 more often than not proved more than the SOC/2gb ram could handle). Couple this with absolutely zero effort put into it's specific software features by the Android team - and you have a red-headed stepchild product. In my time with it, I went from being amazed, to underwhealmed to outright pissed off - and despite my taking it on my own to "help" the software do a better job - without new drivers and official support - things weren't/aren't ever going to get much better.
The N14 on the other hand is in a far stranger but better position. It was the flagship Samsung tablet - for about 4 months, and then the emphasis shifted to the pro-tablets. So it's another red-headed stepchild then? Not at all - the pro tablets are all based on ostensibly the same technology as the N14 - so I imagine keeping it up to date will be far simpler for Samsung (and because it fills a niche that's not so niche) - will likely be kept up to date. That said, we're a couple of weeks out from the pro-tablet lineup and there's no sign of kit-kat for the N14 yet. Likely a marketing strategy to get people to adopt the vanilla 10.1 pro or 12.2 note - I don't see this being a long term problem. So why does that matter? Performance.
Bottom line - the N14 is a much faster tablet than the N10, and has a much better panel (though they share the same resolution) - the biggest difference are Touchwiz and the Wacom digitizer eating up gobs of resources. It's not dog slow, but I'm not going to tell you that it's silky smooth all the time either. So where do you encounter hiccups? It's all in the desktop/ui - once you get an app up and running - it's butter, but getting there can be a bit of a chore.
Hope that helps!
Jack