Usage of Uniform Initialization Syntax

If I have a class

class Foo
{
public:
    Foo();
    Foo(int bar);

private:
    int m_bar;
}

What is the difference between these two ways to initialize it's member

Foo::Foo(int bar):
    m_bar(bar)
{

}

Foo::Foo(int bar):
    m_bar{ bar }
{

}

I was told on a code review to use Uniform Initialization Syntax, i.e. brace initialization. Is there a difference in this case? Or is it just a style preference?