A Kenwood TK-880H means it's the 40 watt version, versus the non-H version which is 25 watts.
Not sure where you are located, but here in the USA the model numbers end with a "K" indicating USA market radios. There is no "1" version, only:
K or HK, which are 450MHz to 490MHz
K2 or HK2, which are 485MHz to 512MHz
and
K3 or HK3, which are 400MHz to 430MHz.
I'd need to have the complete model number of the radio, or a photo of the tag on the bottom to really provide accurate information. Getting the wrong model radio won't help, as they are physically different and cannot be tricked into being something they aren't.
The models available will have one of the following letters at the end of the model number:
L: Scandinavia
Y: PX (Far East or Europe)
K: USA
T: England
X: Australia
P: Canada
E: Europe
M: "Other Areas"
The model/market radios are not necessarily interchangeable and also dictate which programming software you need to use to program them in most cases.
Based on your posts, I gather that you do not have a lot of 2 way radio background. That's OK, but to save you time, money, headaches and possible legal issues, I'd -strongly- recommend you talk to a professional radio dealer about what you need. Simply purchasing an additional radio for your taxi isn't going to be enough. All of these radios will require programming. If you have not programmed a professional 2 way radio before, now is not the time to start. Your license (you have a license?) will dictate exactly how the radio needs to be set up, and in some cases, may even dictate exactly how many radios you are permitted to use under that license. This is where a professional can save you a lot of problems.
I'm happy to assist you, but I'd really need more information:
Your location (city/state/province/country?)
What your license allows
What your level of experience is
What your budget is
At minimum, we can point you in the right direction to get started, and maybe even help you save some money along the way.