It is often the case in our time that the contrast is drawn between being Reformed and being Arminian. Arminianism focuses intently on questions about freedom of the will, human action in redemption, and whether faith comes before or after regeneration. So, Arminianism tends to be a narrowly-focused soteriological concern. Reformed theology, which has existed since before Arminianism and answered the questions posed by Arminianism throughout history, has fundamental and crucial things to say about soteriology and salvation.
It is important that Reformed theology is concerned with more than just soteriology narrowly considered. If we are contrasting Reformed with non-Reformed theology, we are talking about a wider range of issues than the narrow question of Reformed versus Arminian. Reformed theology is concerned not just about salvation narrowly considered. It is concerned with broader issues like the Christian life, the church, and Christians in relation to culture. Reformed theology has many things to say about a variety of important topics, which is what separates it from certain other Christian groups beyond the Arminians.
The breadth and the depth of Reformed theology is valuable because Reformed theology is the most biblical form of theology. Reformed theologians have sought the teaching of Scripture in a wide range of areas, all of which is profitable. So, at the risk of sounding triumphalistic, the greatest difference between being Reformed and being non-Reformed is the difference between being biblical and being non-biblical.
Other groups are biblical in certain areas, but I think there is a consistency to Reformed Christianity that is important.