The most obvious difference that Google Analytics is free, while SiteCatalyst is not. The free version of Google Analytics will process up to 10 million hits per month, which is sufficient for most small businesses. For larger customers, Google offers a premium version which gives the customer access to more data (up to 1 billion hits per month), dedicated customer support, and more customization ability (1). Google Analytics premium pay a flat licensing fee of $150,000 per year. SiteCatalyst does not impose a monthly hit limit on its customers, but their licensing fees depend on their traffic volume and service level so the greater the volume, the costlier the service (2).
Both tools offer a similar mix of features and capabilities. Clients can measure their web-site activity in real-time, see which sites users are visiting, and view how they arrived at the site. They can view historical data, monitor trends in site traffic, and set up alerts to notify them if traffic patterns change drastically or if certain thresholds which the user can specify are met. They both come with a number of pre-built reports and dashboards but also allow users a lot of flexibility to build their own custom reports and dashboards if the out-of-the-box reports don't meet their needs (3,4).
Users can choose which dimensions they wish to report on and which metrics they wish to gather on those dimensions. If you don't know what dimensions and metrics are (like me before researching this blog post), a dimension is simply an object such as a web page, a screen, or a browser. A metric is a measurable number such as screen views or visit duration which describes a dimension. For example, a company may want to see how many views and transactions they receive from their referring websites. In this case, the dimension is referring website and the metrics are page views and transactions.
Each tool comes with a number of basic dimensions, like the ones described above. Sometimes, though, users would like to define their own custom dimensions and metrics to report on. Both tools let users define their own dimensions and then segment their data and build reports based on these. Users can even build reports that compare traffic patterns between segments. Google analytics' website gives an example of how this is done (5). In this example, the customer creates two custom segments based on a URL identifier in the site: men's products and women's products. After the segments are created they can use them in reports. In the example, the report compares the men's and women's clothing segment based on visits, page views, pages per visit, bounce rate, average time on site, or percentage of new visits.
While both tools offer a similar mix of capabilities as noted before, Google Analytics is generally recognized as being more intuitive and easier to use. As discussed, though Google allows some customization of metrics, it is limited compared to SiteCatalyst and somewhat inflexible in the way it detects traffic. SiteCatalyst on the other hand allows users a great deal of freedom to set up variables to categorize and detect traffic however they would like. The downside being that it requires more front-end setup and a more experienced IT staff to use. (6).
Given Google Analytics' price (free), ease of use, and simplicity to set up, it is the choice for small businesses and startups who don't have the money to spend on licensing or IT staff and don't have the time to learn, install, and customize a complex piece of software. SiteCatalyist is the choice for large businesses who need the flexibility and granularity that it provides and have the resources needed to implement it.