They are the same active ingredient of Y-hcl. One is capped with filler at 2.5mg/cap and the other is raw powder.
The caps are not only convenient but safer. Unless you have a scale and are good with making oral solution I advise that you refrain from using the powder.
Effective dosing is as follows: .1mg/lb of bw. This equates to 20mg for a 200lb individual.
Keep in mind that Y can have some adverse effects such as heart palpitations, anxiety and in extreme cases (overdose) hallucinations and or psychotic episodes.
It is advised to be cautious when using this.
I recommend 2.5mg caps 2-3 x per day to assess tolerance and then increase form there if needed.
It is also best used on and empty stomach or a carb free meal as insulin blunts the lypolitic effects of Y.