is there a difference in colon hydrotherapy and colonics?

Hello,

I am interested in bowl cleasing.
I would like to ask you guys some questions.

Is enema the only approach to do the bowl cleanse?
Is there any oral approach?

I am really afraid to inject something back
into my anus.

Besides, what bowl cleasing formula should I begin with?
Actually, now I am using "Yerba Prima". I bought it from
a health food store. I don't know whether it is good.

Please give me your comments.
Thank you.