Sorry it took so long to reply. HF20 kept me from doing anything.
To answer the question, Liquid STEEM and Steem dollars (SBD) are not the same. However, Liquid STEEM and SP are almost the same. SP is simply STEEM stored in a long term storage.
SBD is a promissory note to pay the holder of SBD in STEEM if the holder wishes to cash it in. SBD can also be traded like cash and is essentially liquid.