A secular person is simply someone who does not follow a religious belief system, who believes that all of our attention and energy should be focused on the world as it is today.
A secular humanist, by contrast, believes that our actions should be guided by a moral compass based on human rights and human wellbeing in the here and now. We explicitly reject any “might makes right” moral system that allows individuals or groups to harm, exploit and manipulate others for their own potential gain or agenda.
Secular humanists are also explicitly committed to using science and related evidence-based fields of inquiry to figure out and understand the world we live in.
Points: Not accepting religious claims does not necessarily mean a person accepts a humanistic worldview based on human rights and science.
Fun fact: The increase in secularism in modern democracies does appear to coincide with an increase in humanistic morality, including greater empowerment for women and a significant reduction in the murder rate.