Your Google Account has the following structure: Account / Campaign / Adgroup.
Most of the time you will only need one account which can contain up to 10,000 campaigns (it was only 25 up to recently), 20,000 adgroups per campaign, 5,000 keywords per adgroup, 4 million ads per account, up to 3 million keywords per account. You can do the following on each level:
Mainly to manage who can use the account, along with their rights. You can also manage notifications on a various number of topics like reports, campaign maintenance, disapproved ads, policy or special offers. This is also where you will be able to set the time zone for the account along with the language and number preferences. Finally, anything to do with billing can be found at account level.
Very important level as you can specify where your ads will appear (Google search, search partners, display network), on what type of devices your ads will appear (desktops & laptops, mobile devices, tablets), your daily budget (please note that this is not always accurate as Google can spend up to 20% more than your specified daily budget on a particular day), the way you want to bid (mainly cost per click or cost per conversion, the latter feature being only available after you’ve reached a certain number of conversions for your campaign after which you can specify your desired cost of acquisition for each conversion) and most importantly for most of you, your targeted locations (this tool was recently upgraded to include counties for the UK).
This is basically the lower level of your Adwords account. This is where you will have your keywords, ads, personalised bids and stats (CPC, conversion rate, quality score, clicks, impressions, etc). You will also be able to view the exact search terms people used when clicking on your ads. All in all this is the place to go for everything that’s keyword and ad related.
Adwords Editor is the desktop version of Google Adwords. It’s extremely powerful for bulk changes. For example if you want to change a word or a sentence in ads all across your campaigns, this is the right tool. Creating campaigns in Adwords Editor is also much simpler since you can build your draft in Excel then import it into the interface. Using it will save you a lot of time so make sure you’ve installed it on your computer.