I thought I might choose different shares to hold in my SIPP compared to my ISA account. But I decided that I actually liked the holdings in my ISA and for the most part have added the same holdings into my SIPP - with just a couple of additional shares (e.g SMT & MNKS).
Curious as to whether those who have opened a SIPP are selecting different shares to hold in it, compared to their GIA / ISA accounts?
I go riskier in ISA and sensible in SIPP and any big wins in ISA I transfer cash to SIPP if I have to cash out 
I don’t treat my SIPP holdings and my ISA holdings differently, except that money that I expect to have to spend within the next five years is in my ISAs in the form of short-term bonds and cash. However, for money that I’m willing to place in the stock market, I don’t know of a reason why the mix of assets should be different inside one tax shelter or the other, as long as the overall mix has the right proportions of riskier or less-risky investments. So I have risky and less-risky investments in both ISA and SIPP.
There’s a detailed discussion that can be had about whether you should contribute money into a SIPP first and then an ISA, or fill your ISA allowance first and then contribute to your SIPP, which mostly hinge on issues like your present and future tax band, your likelihood of going over the lifetime allowance in your SIPP, and your workplace pension contributions. Monevator has had some good articles on these issues, such as How pensions will help you reach financial independence quicker than ISAs alone - Monevator, Tax relief upfront is the same as tax relief later: Pensions versus ISAs - Monevator, and SIPPs vs ISAs: pensions knock ISAs into a cocked hat if you want to retire - Monevator.
But isn’t the SIPP a temporary tax shelter? In ISA it is properly tax shelter but SIPP you pay on withdrawal?
Edit - obviously I forgot the added tax relief on the beginning 
Only real difference for me is I have stocks not eligible for ISA (e.g. TSMC) in my SIPP.
My investment horizons for both are long term so they are very similar, perhaps if expected to use my ISA much sooner I might have safer investments there.
SIPPs are an especially good deal for higher-rate taxpayers because of that! (You avoid high-rate tax while you’re working, and most people pay income tax at a lower rate after they retire, so overall you win.)