First, the similarity of both Magento and WooCommerce is that they are both open-source systems, so they can be built upon by any developer who learns to code for that platform. In both cases, there are tens of thousands of professional developers fluent with these systems.
The biggest benefit of an open source system is flexibility. If there's a feature that is not included by default, it is likely that someone has already developed an extension for it, and if not then there is someone who can custom develop this for you. Each platform enjoys the support of a powerful community.
We find Magento sites and developers to be more fluent with larger, complex data architecture, product catalogue with custom fields and attributes. While WooCommerce have come from a mass of WordPress developers who've had success on the front end user experience.
What are the differences between Magento and WooCommerce?
It can be summed up that WooCommerce is slightly less expensive geared towards basic B2C e-Commerce sites. Whereas Magento is the more scalable solution for websites with more products and customization requirements.
So, if you already have a WordPress site and are looking to add e-Commerce, launch with WooCommerce. It will be easiest and cheapest, although not a forever solution, but it can bring online revenues up to the hundreds of thousands. We see many merchants experiencing limitations adding custom features, and migrating to the Magento platform to scale quicker into the millions.
If you're already experienced and have a site on another e-Commerce platform like Shopify, Volusion, BigCommerce, Prestashop, X-cart, Ubercart, Zencart or one of the hundreds of other small players, making the leap to Magento would offer better flexibility to scale to the next level. Mooving to WooCommerce would be more of a lateral move with many similar limitations.