Are they the same thing? tree just like mold on the bread but grows depends on the object size?

Well, they are both living things growing on a substrate that provides nutrients, but beyond that the similarities end.

 

Trees are plants and moulds aren't (they are varieties of fungus).

Tree use sunlight and photosynthesize food. Mould doesn't.

Trees can grow pretty big, but the biggest known organism is a fungus.