Just go for the Acer, it's a good deal. If your laptop screen doesn't bother you for your purposes, you won't care about the differences in viewing angle and color fidelity between TN, VA, and IPS panels, so it wouldn't be worth it to pay the extra for IPS. If your laptop screen does bother you, though, or you just want to learn more, here are the differences between the panel types:
TN (Twisted Nematic):
-cheap; that Acer is a TN, and all cheap monitors are ($250 and under for 1920x1080 or 1200 is cheap, here)
-6-bit color instead of full 8-bit; this usually isn't a problem, since dithering is very good now, but color'll come up in the next point
-Viewing angles are horrific. On my old TN monitor from circa 2007-8, you could easily see color shift between the top and bottom of the screen even looking at it straight on. Because of this, truly accurate color reproduction on TNs is essentially non-existent. If you do serious graphics work of any kind, or think you might in the near future, stay far away from any TN monitor.
-Fastest response times of any panel; a faster response time means the monitor switches colors faster, and thus depicts fast movement better and more smoothly. Slow response times (like greater than 10-15 ms) can cause ghosting.
Examples: Virtually any 23" or larger monitor under $300. Walk into Best Buy or another big box computer retailer and look at their monitor selection - every single one they carry will be a TN. Just about anybody these days makes a passable TN monitor, and I don't think I've heard of anyone to avoid specifically.
VA (Vertical Alignment), including PVA, MVA, etc.:
-Not used much anymore in computer monitors, but some are still made (under panel names such as S-PVA, or Super Parallel Vertical Alignment, and such)
-Better color reproduction and viewing angles than TNs. Good response times as well, so ghosting is fairly minimal on good panels, if present.
-Many suffer from black crush, where dark shades are difficult to distinguish from each other. Especially bad in dark scenes in movies or games, for example.
-Does not suffer from "IPS glow."
-More expensive than TNs, but historically cheaper than IPS panels.
Examples: None that I could find in a cursory Google search.
IPS (In-Plane Switching), including H-IPS, e-IPS, S-IPS, etc.:
-True 8-bit color, like VAs; best color reproduction of any panel type.
-Amazing viewing angles; there is virtually no color shift, even viewed almost edge-on.
-Most expensive of all panel types.
-Suffer from "IPS glow:" When viewed from certain, usually more extreme angles, the monitor will lose substantial black depth and appear to glow. In practice, this is usually not much of a problem.
-Historically slower response times than TN or VA panels, which caused bad ghosting on earlier models. Now that response times have sunk down below 10 ms, this is largely no longer an issue and depends heavily on the person viewing.
Examples: Dell Ultrasharp series, HP ZR series, all professional quality monitors from companies like NEC or Eizo, etc.
The names of each panel type have to do with the arrangement of the electrodes and crystals in the LCD.
Now for your question about response time. Basically all manufacturers quote the the response time as something like "5 ms GTG" or something like that. What that means is that it takes the monitor 5 ms to switch from one shade of gray to another and back. Therefore, response time is a measure of how quickly the monitor can change the color of a pixel, and thus how quickly it can display a new image from some input. A fast response time is obviously important for something like twitch FPS gaming, where you can't have ghost images remaining on the monitor as it keeps trying the update the image. In practice, however, anything equivalent to or better than 8-10 ms GTG should be sufficient for most people to not notice ghosting, but this varies depending on the user. I don't think there are many consumer-level monitors that don't meet this anymore, including IPS panels.