The 1200’s last longer because they have stainless steel parts (and sometimes stainless steel bodies). However, the 1500’s are more versatile because there are no metal parts to touch the sample.
1500’s come in acrylic and PVC; 1200’s come in stainless steel or acrylic only (no PVC). 1200’s have a wider variety of materials than 1500’s. Both come with silicone seals for trace metal sampling or polyurethane seals for general sampling.