What is the difference between encryption approaches in l2tp ipsec on mikrotik?

Question

VPN

There is a screenshot below.

Experimenting and understanding with ipsec and tunnels, such a thing turned out (I know very little about the principle of operation of l2tp and ipsec).
First - This encryption goes inside the l2tp tunnel, between the points of all traffic.
The second is the encryption of udp l2tp traffic, inside of which our tunnel is.
In both cases, if I'm not mistaken, the login / password of l2tp itself is transmitted encrypted mschap2
If anyone can explain. What is the main difference between these approaches? In terms of performance and security. After all, it is encrypted anyway (or you can probably simultaneously encrypt udp traffic on top and encrypt the data inside the tunnel).
Although in the first case, they will not exchange SA until traffic inside the tunnel comes from someone.

Answer 1

It is not very clear what we are talking about, if we are talking about the difference between the tunnel and transport modes, then they do not differ much in the encryption method or in security, but they differ strikingly in the convenience of building a network and in reliability in different conditions.