Hi Jaganathan,
PUSCH/PDSCH mapping types are defined based on the DMRS types supported/used in NR. Below are the two different PUSCH types supported in NR. Supported types are sent via UE capability info.
Type A :
PUSCH DMRS is Type A
The DMRS location is fixed to 3rd (pos2) or 4th(pos3)
PUSCH Starting Symbol is always 0
PDSCH Length can be 4~14 in case of normal CP and 4~12 in case of extended CP
Type B :
PUSCH DMRS is Type B
The DMRS location is fixed to the first symbol of the allocated PUSCH
PUSCH Starting Symbol can be 0~13 in case of Normal CP and 0~12 in case of extended CP
PUSCH Length can only be 1~14 in case of Normal CP and 1~12 in case of extended CP