Is osteomalacia different from rickets?

Yes and no: Normal bone growth and mineralization require adequate calcium and phosphate. Rickets refers to deficient mineralization at growth plates, whereas osteomalacia refers to same deficiency at bony matrix. They usually occur together, however, once growth plates have fused, only osteomalacia occurs.

Yes and No: Osteomalacia implies "soft" bones. It's a term, however, primarily reserved for bone that's become demineralized. Patients with rickets also have "soft" bones, but the primary cause is undermineralization. This is the reason rickets is only seen in very young children. As kids grow, bones become mineralized. Those with rickets can't do that normally, hence the bone is undermineralized.