Ok, I 'll put it the other way around:
Biomaster - Stradic
Biomaster S - no domestic equivalent
Biomaster Mg - Stradic Mg
Biomaster Mg S - no domestic equivalent
Twinpower - Sustain
Twinpower Mg - no domestic equivalent
Stella - Stella
Now there are others with other denominations:
Denomination "HG/PG", for example: Biomaster 1000 HGS; HG/PG indicates a heavy duty reel.
Denomination "S" after the reel number indicates SHALLOW SPOOL, which means the reel has a spool designed for thin lines between 2-5 pound test ( Japan ), therefore the spool capacity is limited if you exceed the line diameter.
Denomination "DH" indicates DOUBLE HANDLE, for example: Sephia 2500 SDH
If you don 't know these denominations when ordering a reel from a Japanese source and you only look at the price you are getting into trouble, the day your reel arrives and you open your box ..... ..... dang ! it 's not what I wanted.
Are they better ? some are just the same reel with different name, others are really different ( for ex Scorpion 1000 vs Curado 100B ) with better upgrades, or lighter gearing ( lighter alloy ) or lighter frame or better cosmetics. Also, in many of them you can enhance the feel or change the cosmetics with aftermaket spools, handles or knobs. Let 's say you don 't like the "T" shape knob in your domestic reel, in most cases you are screwed, the knob is riveted to the handle; in Japanese reels the knob is not riveted but it has a screw, you can change the knob for an "I" shaped knob simply because you can remove the knob.
Do they feel better ? some of them feel the same, others feel a lot better.
Words of advice when purchasing Japanese reels:
1.- Line capacity.- the line capacity you see stamped on the reel is FOR JAPANESE LINES, it does not apply to american lines, if you are using american line reduce between 10-20%.
2.- Read the denomination before you jump all over it and be sure to understand it or you will get a nasty surprise when you open the box.
3.- Shallow spool models DO NOT COME WITH SPARE SPOOL.
4.- Shalow spool models have two line capacities: nylon monofilament ( Japan ) & PE = Poliethilene = braided.
5.- Japanese reels usually have lighter drag.
6.- #1 line means 4 lb test JAPAN.