P Smart Plus has the much better SoC, USB Type C and Quick Charge. Otherwise they do not give themselves so much. Design is of course still a point, but that's a matter of taste.
Personally, I would use the two to the P Smart Plus.
I'll tell you my opinion now, and I hope that I will never make that mistake again, and that I can get others in the right direction.
In April, I bought the Huawei P20 Lite, it's not a bad phone, but what is unbelievably disappointing is that the P20 Lite has cost a whopping 380 Euro! One month later, the Honor 10 came out for 400 euro, kirin 970 … Bigger battery, GPU Turbo, better camera. And since then I regret it!
Then I looked at the P Smart +, new mid-range processor has come to Kirz Kirin 710th The mobile phone costs 300 euro RRP. I could have freaked out! On Antutu, the P Smart + has 138,000 points, the P20 Lite just under 90,000 points (the Mate 10 Lite has only 64,000 points). And yet the P20 Lite cost 80 euro more?
No joke, I would like to dive the phone with 100 euro against the Honor 10.
So if you want the best phone for the best price, then buy the Honor 10, which is now available on the internet for only 340 euro and it's almost at the same level as the Huawei P20. But if you want to decide between the phones, then I recommend you to get the P Smart +.