using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        // No need for Queryables. They're already dictionaries

        var englishResources = GetAllResourceValues(1);

        var arabicResources = GetAllResourceValues(2);

        // Start with all the english words. 

        // Use dictionary because it has efficient key matching.

        var merged = englishResources.ToDictionary( 

            i => i.Key, 

            i => new LanguageResourceModel { 

                    Name = i.Key, 

                    EnglishValue = i.Value.Value 

                });

        // Now merge the arabic ones. 

        // You could LINQ-ify the whole thing, but it's not gonna make it more efficient.

        LanguageResourceModel found;

        foreach (var item in arabicResources)

        {

            // If value already exists, update it

            if (merged.TryGetValue(item.Key, out found))

                found.ArabicValue = item.Value.Value;

            else // Otherwise, add a new one

                merged[item.Key] = new LanguageResourceModel { 

                    Name = item.Key, 

                    ArabicValue = item.Value.Value 

                };

        }

        //debug print

        merged.Values.ToList().ForEach(i => Console.WriteLine($"{i.Name}, English={i.EnglishValue}, Arabic={i.ArabicValue}"));

    }

    // Produce some values for testing

    public static Dictionary<string, KeyValuePair<int,string>> GetAllResourceValues(int languageId){

        if (languageId == 1) //english

            return new Dictionary<string, KeyValuePair<int, string>> {

                {"one", new KeyValuePair<int,string>(1, "one") },

                {"two", new KeyValuePair<int,string>(1, "two") },

                {"three", new KeyValuePair<int,string>(1, "three") },

            };

        else //spanish, cause I don't know arabic

            return new Dictionary<string, KeyValuePair<int, string>> {

                {"one", new KeyValuePair<int,string>(1, "uno") },

                {"four", new KeyValuePair<int,string>(1, "quatro") },

            };

    }

    // and simple class because I'm lazy

    public class LanguageResourceModel{ public string Name, EnglishValue, ArabicValue; }

}