I'm still unclear about your question, do you want to display both texts at the same time or not?
If you're only going to display one 'style' at a time, mayo's answer is right. You can use a switch statement to implement it:
switch(textStyle){
case 1: myTextView.setTextAppearance(getApplicationContext(), R.style.styleText1);
break;
case 2: myTextView.setTextAppearance(getApplicationContext(), R.style.styleText2);
break
}
More info here.
But if you want to display both at the same time, a WebView is your only option:
Webview wv;
//Specify Text1 and Text2 as strings.
String text = "<html><body style=\"font-size:25px;\">"+"<p align=\"center\">"+ Text1 +"</p>"+"<style=\"font-size:15px;\">"+"<p align=\"center\">"+ Text2 +"</p>"+"</body></html>";
wv.loadData(""+text, "text/html", "utf-8");