What is the difference between an "ice-breaker" or a "warm up" when teaching an ESL class?

Teacher uses ice-breaker activity at the beginning of a new course so that learners can get to know each other, while warm up is an activity that a teacher uses at the beginning of a lesson to give the class more energy.

Hi Aisha! Good question. Both activities are intended to get people/students to engage with one another. In your case, they're good opportunities for students to practice their English skills. Ice breakers, in general, are activities that allow people to step out of their comfort zones and get to know one another. Whereas, a warm up is a little more restricted. In this activity, an individual thinks of an object and the group is to guess what it is by asking questions. However, they cannot ask "wh" questions: Who, What, Where, Why, When. So, they could ask: Does the object talk? 

I hope this helps!