This guide aims to summarise differences between different thinkpad models. Most of this will probably only be accurate for T400 era models and onwards. I don't own the majority of models being described, so you should do your own research - errors most likely exist. Contact me at thinkshit@cock.li if you find any.
The X1 Carbon isn't covered here yet but it's also probably worth considering.
Table below details some significant differences between models. Specific to 2nd and 3rd generations. All models support mPCIE/mSATA and ExpressCard on top of more ordinary features. (Todo:dimensions, weight, battery life)
| Series | Size | CPU Soldered? | Ultrabay? | Max RAM | Max Resolution |
|---|---|---|---|---|---|
| X | 12.5" | Yes | No | 2x8GB | 1366x768 IPS |
| T | 14" | No | Yes | 2x8GB | 1600x900 |
| T(s) | 14" | Yes | Yes | 2x8GB | 1600x900 |
| T | 15.6" | No | Yes | 2x8GB | 1920x1080 |
| W | 15.6" | No | Yes | 4x8GB | 1920x1080 |
T series thinkpads make for well rounded work machines, aiming to give a great experience during actual use. Portability takes the backseat, at least with older models - 14" models should be easily manageable for most in terms of weight and bulkiness, but they were hardly designed with these as a priority. Battery life probably won't be spectacular without an extended battery, particularly in models without ultra-low-power CPUs.
Two form factors are available in the T series - 14" (T4?? models) and 15.6" (T5?? models). The main difference is simply the size of the screen, and the panels available. 14" models usually have an option between a HD (!1366x768 or similar) panel which has terrible viewing angles, or a HD+ (~1600x900) which is an all round improvement. 15" models have similar resolutions but also have the option of a FHD panel, which can be an improvement in various regards. Later models offer higher resolutions for both sizes, and can also have additional battery cells in the 15" models. 14" models are the most common, and will likely be cheaper and better suited for most due to portability.
Alternative versions: s models (T420s, T430s, etc) are more compact, and have a soldered CPU and different battery form factor, with HD+ screen as standard. i models (T420i etc) are budget models and generally rubbish. p models (T460p etc) are workstation models that feature better CPUs and probably other things I'm not aware of.
Recommended Models: T420, T420s, T430, T430s. 15" versions are also fine if portability is a minor factor.
X series thinkpads are designed for portability, sporting a 12.5" screen, soldered CPU and no ultrabay. These are especially recommended if portability is important to you and making vapid modifications to your thinkpad is not. The smaller screen means a longer battery life, but the screen itself is limited to 1366x768 on earlier models. IPS panels do exist, offering vast improvements to colour reproduction and viewing angles.
Tablet models exist - these have a touch screen (which is always IPS) and WACOM stylus, and the screen can be rotated on extra axis to convert the laptop to a tablet form factor.
Recommended Models: X220, X230, Tablet versions of these if you'll use it
The W series is the thinkpad mobile workstation line. These boast high end i7 CPUs, workstation GPUs, up to four DIMMs of memory (up to 32GB), and screens with high resolutions and good colour reproduction. Portability is not a priority, with larger volume and mass than an equivalent 15" T series. Battery life will likely also be the worst on offer. W series thinkpads are suitable where high performance processing or graphics are needed, or otherwise where the high quality screen can shine in applications like graphics editing. Outside of these needs, W series tend to be more expensive as well as less portable and thus won't worth your while.
Filling of the workstation role varies a bit -
Recommended Models: W520, W530. The W530 seems to be barely more expensive than the W520 in some markets so ymmv. Later models also get the option for a 3k panel (which you can get from china for cheap) but prices ramp up hard with the W540.
Advantages:
Disadvantages:
Models of this generation are definitely capable, but rarely cheap enough to justify choosing them over new ones given the immediate improvements to everything but screen dimensions.
Advantages:
Disadvantages:
Models of this generation are mostly no longer in use in corporate environments, thus they're readily available for cheap. There's no major issues with them and will do any mundane task with ease, though if you need performance then the small price increase to the next generation might be worthwhile to you.
Advantages:
Disadvantages:
Models of this generation are beginning to be discarded by companies and thus the price for them is approaching that of the T420 generation. The improvements this generation offers in regards to the processor are somewhat minor, but the GPU is a fair step up and overall power use is down. Since after this generation, the design changes significantly and U model CPUs become common, I'd recommend spending a little more for this generation just to have the best of the more classic thinkpads. The one caveat is the keyboard - if you prefer the classic keyboard you'll need to swap one in, and they're not particularly cheap.
Advantages:
Disadvantages:
This generation is starting to become cheap but is yet to actually become reasonably priced. All it has going for it is battery life, which is actually a decent step up, but otherwise the processors are less powerful and the trackpad is shit. Get a 5th gen if you can.
The W540 doesn't use a low power processor, and now also features a 2880x1620 IPS screen. While it does have the shit trackpad, it might still be worth considering given the W550 will be an even bigger step up in price.
These are much like the previous generation but the trackpad seems to be of better quality even if the essential design remains the same. Processor performance is about equivalent to 3rd generation performance depending on benchmarks, though battery life is of course much better. This generation is still sold new by Lenovo so you may struggle to land a good deal given that companies aren't offloading them, but finding cheap 2nd hand specimens coming from individuals isn't unheard of.