A job is something you do to collect a paycheck. Important, but uninspiring.
A career calling is something you do to fulfill a desire to make a difference in this world. It's not a separate identity you assume for 8-10 hours a day. It's part of who you are, an outward expression of your inner values. It doesn't have to be glamorous work, but it does have to have meaning and purpose to you.
The only real difference between the two is your attitude toward it. You can do a job, or you can have a fulfilling career, showing up for work every day ready to make a difference. Here's a simple example:
Yesterday, I went to a real barber shop for the first time in my life. It's a small, unassuming mom-and-pop shop about a block from my apartment. The barber cut my hair like I was going to see the president. He talked with conviction about giving the perfect haircut. Conviction about cutting hair -- who would have thought? It's probably no surprise that I got one of the better haircuts I've ever had. The biggest surprise: they don't accept tips. It's not about money for them, it's about doing great work. Guess where I'm going to get my hair cut from now on.
Too many people wake up each day and go to jobs. Considering the amount of time we spend working, our lives would be so much more fulfilling it we had purpose-driven careers. If you feel stuck in a job and desire a career calling, you basically have two options. You can find new work, or you can change your attitude toward the work you do.