First, very importantly, you should make sure the exact CPU inside the HTPC you purchase, many seller write only i5 or i7 without other informations, exactly it should be i5-4200U, i7-4500U or other similars. When get the CPU details, you can learn directly from intel.com to check CPU details if you feel the informaiton on the sellers site not clear enough. You can find the memory types it support directly as shown like this picture:
Now lets see difference of DDR3, DDR3L and LPDDR3. Laptop memory is 204pin(SO-DIMM DDR 3) and destop memory is 240 pin(DDR 3).
Here is summarization of the key differences
Now lets see difference of DDR3, DDR3L and LPDDR3. Laptop memory is 204pin(SO-DIMM DDR 3) and destop memory is 240 pin(DDR 3).
Here is summarization of the key differences