To avoid confusion - I base my understanding of the term 'Hinayana' on Andrei's answers to two different questions - this and that.
Hinayana way (or as Andrei puts it - level) refers to basic/elementary/foundational aspects of Buddhism. On this level precepts are central and students learn to follow basic discipline. The main idea is to work with one's own Karma - having a simple life protects one from difficult situations and clear-cut rules help in achieving that. However, this is not all that Buddhism offers. Once the foundations are understood, one can move on to more advanced teachings which can be called Mahayana-based (as Andrei pointed out, this can also happen in Theravada).
The main difference, as I understand it, is that it is the Bodhisattva Vow that is central in Mahayana level. Here, one is no longer worried about one's own Karma (like on the Hinayana level), but recognizes that there are countless beings who suffer and one wants to benefit them in the first place. One does not need a precept to know that killing or lying is bad. In every situation one has to be mindful and decide which action will bring more happiness or suffering to other beings. Sometimes lying is the right way to protect someone's life, sometimes eating enormous amounts of roast beef is the best way to make our auntie happy after she spent the whole day preparing this dish for her beloved family. No clear rules, rather guidelines and constant wish to benefit others.
I believe it all boils down to motivation - if you observe the precepts in fear of spoiling your own Karma - it is Hinayana level. If you are mostly interested in benefiting others - it is Mahayana. One view violates the other one.