If you’re thinking of getting an Apple Watch, you’ll need an iPhone because you can’t pair one with an Android phone. Assuming that doesn’t put a spanner in the works for you, here’s how the Series 3 compares to the (now discontinued) Series 2.

What’s the difference between Apple Watch 2 and 3?

Put simply, the Series 3 has a faster processor and – optionally – built-in 4G. In almost every other respect, it’s basically the same as the Apple Watch 2. Of course, there’s a lot of clever engineering inside to pack in an LTE modem without making the new Watch bigger but – from your point of view – it looks pretty much exactly the same. To clarify, there are two main choices when you buy an Apple Watch 3: you get the GPS-only model or you pay extra and get the GPS + LTE model. There are lots of versions including the Nike+, Hermes and the Edition (which has a ceramic case), and two sizes: 38mm and 42mm. This means prices vary a lot. And because the LTE version needs data, you can also pay for it monthly from mobile operators such as EE (the only UK operator to support it), with no up-front cost. For more details, see where to buy the Apple Watch 3. This handy table shows at a glance how the two watches compare. We’ve included both versions of the Series 3 to make your choice even clearer. If you’re in the US, prices are the same in Dollars.

So which Apple Watch should I buy?

As you can see, it’s the inclusion of a 4G modem that sets the Apple Watch 3 apart from the Watch 2. It will automatically use its built-in e-SIM when it’s too far from your iPhone and allow you to make and receive phone calls and send and receive messages. This all happens on the same phone number as your iPhone, so there’s no hassle of having to juggle two numbers. However, it will cost you £5 ($10) per month extra (with the first six months free) to add the Watch 3 onto your phone tariff and the bad news is that – at launch – it will only work on EE in the UK. You can either buy the Watch directly from EE on contract, or buy it from another retailer, like Apple, John Lewis, or Currys, and then connect it to the EE network – assuming EE provides your phone service already. If you’re on another network you’ll have to switch to EE in order to use the cellular functions on the Watch 3, or wait until the exclusive period ends and other operators begin to support it. If you’re in the US, the best bet is to buy the Watch from Apple or another retailer, and then sync it to your network – it will work with Verizon, Sprint, T-Mobile, or AT&T. Do note that the Apple Watch 3 LTE does not support roaming, so any additional features enabled by the e-SIM will not work abroad. Aside from the data, the Series 3 has a new processor that Apple says is up to 70 percent faster. That’s good news from a future-proofing standpoint as apps always becoming more demanding of processing power. It also allows Siri on the Apple Watch 3 to talk. On the Series 2, Siri can only display messages or search results on screen. It’s a very useful improvement. You can’t buy an Apple Watch 2 from Apple any more, but it’s still on sale in plenty of shops including John Lewis. Prices haven’t dropped yet which means that the non-cellular Apple Watch 3 is actually cheaper, so until retailers slash prices to clear stock, you might be better off getting the Series 3 which has twice the storage capacity (16GB vs 8GB). If prices do drop significantly and you don’t need 4G in your watch, then you might be able to grab a Series 2 for a better deal than a Series 3. But remember that the processor in the Series 3 is faster, you get twice the storage and an altimeter (for measuring height climbed). Apple still sells the Series 1, starting at £249, so it unlikely you’d find a Series 2 cheaper than that, so whether or not you should buy one depends on how much you value the new features in the Series 3.  Buy the Series 3 Apple Watch. Jim has been testing and reviewing products for over 20 years. His main beats include VPN services and antivirus. He also covers smart home tech, mesh Wi-Fi and electric bikes.