Being invited to apply as a Barrister and being invited to apply as a Solicitor are two identical routes by two different names. They both have the same skills assessment requirement, which is admission as a lawyer in Australia.
Both occupations are WELL within their occupation ceilings. So your main concern should be maxing your number of points to be invited not which occupation to apply under.
2711
Barristers
1,000
<5
2713
Solicitors
4,650
27
Hope that helps, good luck.