In today's American discourse, in both culture & religion, the terms "evangelical" and "fundamentalist" are often used interchangeably, both of them contrasted to terms used to designate those who lean to the left regarding faith issues, who are often termed "liberal" or "progressive". I believe there are stark differences between "evangelicals" & "fundamentalists" & that this distinction is vital to understanding today's Church, particularly in America.
The evangelical movement (or neo-evangelical movement) was birthed out of fundamentalism in the mid-20th century. Originally known as fundamentalists who were willing to cooperate with non-fundamentalist Christians for evangelism & mission work, the movement quickly broadened & soon began gaining adherents in the very mainline denominations fundamentalism was founded to fight.
Because of the breadth of evangelicalism, identifying core principles in this
trans-denominational movement can be difficult. Wesleyan evangelicals, for example, stress the importance of God's prevenient grace, Lutheran evangelicals stress Luther's delineation of law & gospel, Presbyterian evangelicals stress the sovereignty of God, Catholic evangelicals stress proper celebration of the sacraments, Pentecostal evangelicals stress the gifts & activity of the Holy Spirit, Baptist evangelicals stress their particular understanding of baptism, etc. These & other differences are not unimportant.
But what evangelicalism has become, essentially, is a movement which strongly adheres to the core principles of orthodox Christianity as it has been proclaimed for more than 1500 years. The doctrines of the Trinity & the Incarnation are important, as are the Resurrection of Jesus & the authority of Scripture. Evangelicals may disagree as to which atonement theory is to be preferred (ransom, Christus Victor, Anselmic satisfaction, Calvinist satisfaction & governmental approaches have all been taught by evangelical theologians at one point or another) or which style of worship is most faithful or what is the correct understanding of the sacraments or which polity is best, but they are united in that core doctrines such as Trinity, Incarnation & Resurrection are vital to being Christian.
Fundamentalism has also broadened a bit, but not in terms of cooperation. There are Catholic fundamentalists, for example, who insist that unless one is a faithfully practicing Catholic, one is not a Christian even if adhering to the core doctrines of the Great Tradition. Some go further & believe that unless one is a faithful "traditionalist Catholic" rejecting Vatican II & everything which followed, one is not a Christian. There are similar movements in, say, Reformed Baptist circles, where some teach that unless one adheres to Dordt Calvinism, one is not Christian (which begs the question of how any Christians could have existed prior to 1619). Fundamentalism is thus still generally known as an at times nasty approach to culture & the Church, misunderstanding or even ignoring completely the love of God & the fullness of his grace. Put another way, too often our fundamentalist sisters & brothers "major on the minors".
To understand the full breadth of evangelicalism / orthodox Christianity, perhaps no work has been more important than that of theologian Thomas Oden, who has endeavored for decades to gather the wisdom of the ages for the Church to learn & enjoy again. I highly recommend his Classic Christianity as perhaps the best one volume summary of the Great Tradition in the English language. Here, we read of the fullness of orthodox Christianity & rejoice in its diversity as well as its unity.
I am an evangelical Christian in a Wesleyan context. It's a wonderful thing to be.